Well, it's like comparing Brawl to Melee. Melee brought a onslaught of awesome stuff, and Brawl just rehashed it with extras that were useless and a near unplayable online with new characters, and switch the aerial dodge to make the character roster unbalanced and make you do the same moves over and over
That's pretty much what Gears 1 to gears 2 is like, only I think Gears 2 made a few gameplay enhancements instead of drawbacks, the online was really unbalanced, which is why it pretty much sucked, but they patched it online, so it's more balanced now. Chainsaw was really cheap, I'd just go around murdering people with it like a Friday the 13th Movie before the patch.