I'm impressed!
I'm impressed, and I'm a rather picky gamer.
The controls are simple but allows for a rather wide array of ability. The sound is pretty good (though I cried at the Megaman voice when he jumps) and the visuals are decent, and the gameplay is pretty close to the actual Super Smash Bros. games.
You've managed to capture the original spirit of the SSB game, and I wound up playing this for hours on end when I first got a hold of it. I'm rather impressed; this extremely picky gamer gives this flash game a gold seal of approval and two and a half thumbs up.
Normally I'll pass over Flash games as I get tired of them easily. This one got tired of me first (I played it so long it somehow managed to crash IE!).