I love Solid Snake. And MGS2 was like a theatrical masterpiece to me.
But that's the problem. It was theatre. The game itself, while it contained many tiny, amusing little secrets and quirks in the enemy AI and stuff... it was just too damn easy (in the normal modes, not the insane one.) It's hard to stumble on those fun little details and add-ins, because they aren't the games focus. You move around and choke people, then fight some easy patterned boss.
Don't get me wrong. MGS2 is one of my favorite games. But SSB:M was awesome. Forget that it was cartoony, forget that there were two attack buttons; it was addictive, the play was actually very skillfull, and it just had loads of variety, unlockables, and everything you could ask for. Normally I don't give a crap about Nintendo games but this one was a definite classic. If you have friends and you have this game, you will NOT get tired of it. Ever.