Alright, here's to hoping my post doesn't drown in the sea of crappiness that overwhelms this thread.
In my opinion, with the exception of a few characters, Brawl is more balanced and easy to get into than Melee. Besides obvious bad matchups (and a few bad characters, heh) I have no problem beating any character with any other character. I'd say 80% of the characters are incredibly close together on any theoretical tier list, with the other characters being semi-broken/broken (they can still be beaten, of course) or mysteriously crappy. (I still love you, Falcon.)
The only characters I get an overwhelming sense of dread playing as (WHY DID I CHOOSE HIM!?) in Brawl are Captain Falcon and Jigglypuff (I suck as PTrainer too though), and it's still fairly possible for me to beat people with him. (Not Metaknight.) In Melee, if I chose anyone other than the better characters, I got a sudden sense of dread that I was going to lose. I'm sure that if I was dedicated to them and practiced a fair amount the feeling would go away, but I main Random. When playing as Kirby, Pichu, Mewtwo, or Ness gives you a feeling of "oh crap," it's not a very good sign of the game's balance. (I felt this way before I even read about any tier list.)
So, the difference between a crappy character and a good character was astronomical in Melee. So, why could a really good Mewtwo beat a great Falco? The answer: ATs and Mindgames. Melee had an incredibly technically deep fighting system that allowed for an incredibly high "skill ceiling." This allowed players to be better than the other nearly without limit (we've practically reached it now), circumventing the differences between the tiers. (please don't point out that said mewtwo played with the falco all the time and that there were other reasons for the victory, it's just an example)
Now, look at Brawl. Brawl has very few useful ATs, and those that are useful are either highly situational or so easy they're not really ATs. For all intents and purposes, Brawl really only has "mindgames." The technical skill ceiling in Brawl is very low, and while increased technical skill is helpful, the lack of hitstun and increased defensive maneuvers greatly diminish its benefit from Melee. Brawl only has mindgames. Brawl is all about mindgames. After you've got the spacing done, then it's just mindgames. While it's possible to be the greatest at mindgames (pretty hard if you ask me), "mindgames" is a really vague term that can't be measured or be gotten better at in any tangible form. Therefore, the skill ceiling on Brawl is and will remain low.
Despite the fact that the tiers are closer together (even between broken and non-broken, really!), the lower skill ceiling lets the players themselves advance less beyond each other. This, in turn, makes the tiers yet again horribly, horribly evident between the bottom and top. The (hopefully large) middle-high tier will still probably be very close and make little difference, but as the players continue to reach the limits of their skill and it becomes harder and harder to become better at the game, tiers will make more and more of a difference, slowly breaking the game.
Of course, Melee's already been broken from the start, but at least it was honest about it.
Anyway, this also explains why on day one (when the skill ceiling seemed very high and improvement was random and drastic and progress had not yet slowed because you were at the bottom) everything might have seemed balanced besides perhaps a few random techniques but as the game progresses people wonder what happened to the "balanced" gameplay that they encountered at E-4-All.
I like both Melee and Brawl equally.