Bloom, nades, and melee seem to be the biggest and most consistent complaints so far. IMO, this is due to the fact that if you played a lot of Halo 3, and jump into Reach and attempt to play it like Halo 3, you are going to get your ass kicked mostly due to the bloom, nades, and melee changes. Just because you suck at Reach doesn't mean Reach sucks. Learn how to play the game and then complain if you still don't like it.
Also, btw, no one gives a shit whether or not you are going to buy Reach or continue to play online gaming, so please stop whining as if anyone cares.