It's hard to write about This is Spinal Tap when just about everyone under the sun has seen it. But why is it so good? What makes it something that people recommend to others to view? Is it strictly for its humor? It is, after all, possibly most the original and one of the funniest American comedies made over the last quarter century. Fans have been repeating the lines in it for years because some of them have transcended the movie itself. "There's a fine line between clever and stupid" reflects more than the observation of fictional British rockers, doesn't it? However smart catchphrases do not a memorable movie make. Fortunately This Is Spinal Tap works on many other levels.

For those unfamiliar with the film, it was written by Saturday Night Live alums Christopher Guest and Harry Shearer (not to mention longtime friend Michael McKean of A Mighty Wind fame) and directed by a young Rob Reiner (Sleepless in Seattle). Reiner appears in the film as aspiring director Marty DiBergi, who follows the adventures of the British heavy metal group Spinal Tap through their North American tour in support of the "Smell the Glove" album. Guest (guitarist Nigel Tufnel), McKean (guitarist/vocalist David St. Hubbins) and Shearer (bassist Derek Smalls) are the principal members of the band. The band, the tour and everything else associated are fictional, but the filmmakers approach it from a documentary point of view, or as DiBergi says in the film's first few minutes, a "rockumentary," though fans would likely call it a "mockumentary."

Since its 1984 release, This Is Spinal Tap remains a layer cake of awesome. Devotees of music groups and/or documentaries of music will notice so many similarities to events that happened in that era captured so brilliantly on film. From Aerosmith to Anvil, you see stage mishaps, underwhelming promotional appearances and cancelled appearances, all hilarious for many reasons. When it comes to real life, Tap's revolving door with drummers may be exaggerated, but when you consider the antics of The Who's Keith Moon and Led Zeppelin's John Bonham in (to mention the virtual cavalcade of deceased musicians from) the '70s why not take their deaths and make them funny? Within the spectrum of spontaneous combustion and choking on someone else's vomit, I laugh every friggin' time.

The subtleties in Tap when compared to other rockumentaries are equally precious, and I think it's due to dedication to the bit that the cast and crew share. They don't break character during the faux documentary and manage to capture a certain content obliviousness similar to many musicians of the '80s seemed to share who would take any question in stride and seem would incessantly babble on. Nigel and David will take any question and roll with it, but the great part is that the beginnings of their answers sound pretty much like anything else you'd hear from a real person; it's the running into drivel part that results in laughs. Even if you aren't familiar with hard rock documentaries, it's funny.

It's this continuing sincerity that also helps pull off what is the most poignant aspect of the film: the friendship of Nigel and David. Chums since childhood who have creatively clashed heads in the past, things tend to be a little different when David's girlfriend Jeanine (played to perfection by June Chadwick) joins them during the tour. Jeanine doesn't mean to be disruptive to their collaboration, but as the tour wears on and the disappointments mount, her intrusions have David under a spell of sorts, not unlike the disruption that Yoko brought to John and Paul. Watching the David and Nigel partnership is not only touching and possibly the heart of the film, but helps carry the film past the jokes.

Ultimately, This Is Spinal Tap is a brilliant comedy mixed with biting satire. Over the years, some bands have claimed things in their lives to be "Spinal Tap" moments as some sort of grasp at recognition. Other lesser known bands have lived through some of Spinal Tap's trials and heartbreaks, and they may not be funny to them at all. The film is also a nice story about two blokes who might be on hard times, but they won't let a perceived outsider get in the way of their true creative happiness. It's funny, it's memorable and it's enduring. It's so many things, turned all the way up to eleven.

The BD-50 disc on which This Is Spinal Tap is housed is presented in its 1.85:1 widescreen glory with the AVC MPEG-4 video codec. The feature appears to have been shot mostly with handheld film cameras, equipment as good as you could probably find in 1984. The color palette is reproduced accurately here, but the colors themselves aren't very vivid, and nothing stands out. There's no multidimensional feel in the image and the difference between this and the standard-definition release is marginal. Boo.

The DTS-HD Master Audio lossless 5.1 surround soundtrack isn't anything to write home about either, though it's at least better in the musical performances. Guitars stay fairly focused in either channel, but drums are a little bit weak, and the subwoofer picks up the low end for Smalls' bass when necessary. Considering the age of the feature, I was impressed that the concerts could still pack such a punch. The sound isn't too enveloping in any other sequence though, but This Is Spinal Tap is solid sonically.

MGM has brought over the extras from 2000's Special Edition, and has added a standard- definition second disc with more extras, which seems to scream "Look, we put some more work into this!" to the consumer. However, the extras are boring. The first is the band playing "Stonehenge" at the 2007 Live Earth concert in England. With introductions by DiBergi (and before that, Ricky Gervais) prior to the song, the extra is just under seven minutes in length, and unless you REALLY want to see the full-length song, you're not missing anything. The other piece is an interview with Tufnel that was conducted for National Geographic television (8:35). Like "Stonehenge," this is supposed to be fun, but comes off a little more sad than anything else.

The MGM extras are entirely on disc 1, starting with an in-character commentary from "Nigel, David and Derek." First off, they proclaim the film to be a hatchet piece from DiBergi, and anytime the fictional director comes on screen, the trio mocks him and whatever approach he may be taking to a particular scene. The general crux of their argument is that he only showed the 1 percent of bad stuff while ignoring the other 99 percent of good stuff. They also spot the people who are still around and those that are dead, including random extras such as the Chinese guy in the deli. Nigel (I believe) has the quote of the track by saying "In retrospect, hindsight is 20/20." It's worth an occasional listen to enhance the Tap experience.

Following that, "Catching Up with Marty DiBergi" (5:01) is an interview with Marty now, showing where he is and what he's doing. The big extras two pore over are 14 deleted/extended scenes (1:07:51), some of which help show off the supporting cast, which includes Dana Carvey, Billy Crystal and Bruno Kirby. A press conference for the then-Flower People is next (1:49), which is funny in a satirical Gimme Shelter kind of way. Tap also appears at the end of the Joe Franklin Show (a local New York broadcaster similar to Tom Snyder) to plug their album. Four funny music videos are next (12:21) which are funny and frighteningly real; they could step into some videos from KISS or Ratt and not miss a beat. Two trailers (3:20), which show virtually nothing in the film are next, (the trailers are hilarious), and six other promotional spots (three TV spots and three commercials) conclude things.

Honestly, there's nothing within the Blu-ray release of This is Spinal Tap that's all that exciting. If you already have the MGM release and double-dip for this version, you'd be paying for a decent lossless track and 15 minutes of extras that you won't watch unless you're a hardcore Tap fan. It's not worth it. However, if you don't have a copy of the film, or if you've never seen it, what the hell are you doing reading this? Go out and get it!