Reach is okay and I enjoy playing it, but it isn't as good as Halo 3 in my opinion.
It's propably because the maps in Reach suck. Not all of them, but most of them do. Bungie made a bad move when they decided to take the maps from campaign. Now they look boring and unimaginative and their layouts are horrible. Why they just couldn't do separate maps for multiplayer, like in Halo 3 and 2? I guess they ran out of time or got lazy.
Another thing that bothers me is that it's a little slower than Halo 3, but it isn't that much of a problem for me, unlike the previous issue I mentioned.
[Edited on 10.03.2010 7:45 AM PDT]