Seems like everyone else is running their impressions of Eastwood's movie early; so I'll jump in. I may or may not have more in-depth to say in a colyumn at some point, but for now here goes...
"J. Edgar" is pretty much what one expects both from Eastwood as a director (great performances, terse no-bullshit direction, comprehensive "and then this happened..." plotting and a detached-to-the-point-of-"funerial" tone) and from a present-day biopic about J. Edgar Hoover (grim, scheming and bitter.) It doesn't have much "new" to say about the man or the era he lived, and the main selling-point will be DiCaprio's Oscar-worthy lead performance, but there's nothing "wrong" with it and it's a solid, thoroughly-engaging - if not precisely "entertaining" - work.
If it has an "issue" it's that it'd be difficult to make a "fair" biopic about Hoover that wasn't just a little bit unpleasant to sit through, since Hoover himself was - by even admiring accounts - a fairly unpleasant fellow to be around. The film doesn't deviate very far from the generally-accepted view of the late FBI-founder: Repressed, paranoid, obsessive, arrogant and opportunistic; and to it's credit it presents the sketchier aspects of his methodology - secret files, wiretaps, legal-circumvention, outright fraud and deception - as both innovative and effective (i.e. against the anarchist-bombings of the 20s and gangsters in the 30s) and as petty and fiendish (i.e. his fixation on MLK and The Kennedy Brothers.) Incidentally, somebody needs to tell Kevin Costner that "Burn Notice's" Jeffrey Donovan, as Bobby Kennedy, has stolen his title as owner of the worst New England accent ever committed to film.
It also doesn't reach too far outside the box for an "explanation" of the man - Dustin Lance Black's screenplay is couched comfortably in the widely-rumored thesis that Hoover was a profoundly-closeted homosexual, and that his innability to accept this (along with his myriad other "issues") stemmed from his relationship with his cold, controlling mother. The central relationship is between Hoover and his longtime companion Clyde Tolson (Armie Hammer) who is depicted as having a more self-aware grasp of the nature of their friendship than Hoover himself does.
Interestingly (and possibly without direct intent, since Eastwood has never been one for showy symbolism) it's the small scenes of Hoover breaking his own stone-cold facade in regards to said relationship (and/or his sexuality, such as it is) that the film itself briefly breaks free of the Eastwoodian straightforwardness and attains a kind of melodramatic earnestness; and it stands in such direct contrast to the rest of the film the effect is almost like minimalist-"camp" (critics at my screening compared it to "Mommie Dearest.")
The big showpiece scene, Hoover and Tolson having an unconsumate "lover's quarrel," is almost quaint (approaching caricature) in it's Eisenhower-era rendering of gay men - DiCaprio and Hammer dolled up in slicked-hair and monogrammed bathrobes (!) having a catty back-and-forth about their friends' taste in shoes (!) and escalating to a screaming brawl when one of them mentions a girlfriend (yes, brandy-glasses-hurled-at-the-walls; yes, big cowboy-style haymakers) complete with bloodied kiss and awkward backpedaling. In another, Hoover grieves his dead mother by donning her robe and pearls (you knew it was coming) and talking to himself "as mother" in the mirror, Norman Bates style, before crumpling up into a sobbig fetal position.
If there is ONE thing that doesn't work at all, it's some of the makeup. The film leaps back and forth through Hoover's life and career without the aid of subtitled dates; relying on multiple stages of old-age makeup to clue us in to where/when we are... and it only looks good some of the time. Naomi Watts (as Hoover's secretary Mrs. Gandy) has the most subtle work of it, though she seems to be aging about 1/2 slower than everyone else. DiCaprio actually fares best, which is appropriate, though given how differently the public tends to percieve him as an actor (re: an "eternally boyish" guy who's actually approaching middle-age and DOES look it sans makeup) it's possible that he NEVER appears fully "himself" over the course of it - his final "elderly" appearance makes him look an awful lot like John Voigt. Sadly, Armie Hammer is just a little too young (a DECADE younger than DiCaprio) a little too tall and in far too good a shape to be plausibly transformed into an elderly man for the later scenes. His performance is fine, but the makeup-appliances make him look like a zombie as opposed to "old."
Overall, it's one of those movies that's more "admirable" than "likable," but probably more worth seeing than a lot of what'll be out right now. Plus it's going to be up for a boatload of awards so you might as well.