Wow, I never thought I'd say this, but I actually agree that in summation, the experience is.....okay. I don't think this stuff counts as "spoilers" because it's stuff you notice from the start.
1.) The two-handed thing doesn't do it for me, and here's why. First, it's unwieldy--I hate having to go through a series of button pushes when the gun I want to keep is in my left hand. Second, it takes grenades out play, which--to me--were a HUGE part of Halo 1 tactics. Third, many of the enemies are so much tougher in Halo 2, you can't hope to kill them with a single pistol, essentially mandating that if you are going to have a sidearm equipped, you HAVE to have two or you WILL die.
2.) I don't think the variety of weapons is an improvement. In the first game, the limited number of weapons was part of the fun (e.g. if the other guy had a shotgun, you got a stand off weapon, etc) I mean the pistol and the energy pistol are now completely neutered--you can't kill anything with either. If you wait all day to charge a plasma pistol power shot, the things don't home in worth a damn. What's up with that?
As far as I can tell, the only human weapons worth having are the rocket launcher, shotgun, and sniper rifle. All the others suck--the pistol is pure ass, the semi's have dubious stopping power and are slow to reload, the new assault rifle is also lame.
The new covenant weapons are better--the plasma sniper rifle, the fuel rod cannon I can live with. I think the one-hit kill sword is overrated because you get so few kills with it. The carbine seems to suffer the same problem that the human assault rifle does--too little ammo.
In fact I have to say that overall, you don't seem to get nearly as far with one weapon in this game as you did in the original and that's a shame. There's simply no reason why it should take two head shots to kill those armored grunts.
I dunno, I'm coming off negative and I don't mean to, because overall the game is a net positive. I like the new art, though many of the levels were too dark. The vehicle rides got a little boring at times. The story tended to skip around a bit more than I would have liked, but there's no way around that I suppose. The main criticism I have is that the new controls detract a little from the magic of the original. We bassists know that less is more.
Well, off to the real reason we all bought this bad boy in the first place--online play. See you in the ring.