Only played about 5 different matches (All on Sword Base. Good thing I don't mind it.)
I'm definitely enjoying it more than Halo 3 Multi, which I've only played sporadically since it launched. A few things, which are probably repeats of others (Keep in mind, I'm a -terrible- Halo player, so yeah.)
Invis: Either I'm missing something, or Invis is completely broken. Everytime I've tried it, I'm automatically spotted. On the flip side, I'll run into a guy on the other team who has it and he looks like he's a ghost. All see through, but not really hard to see at all.
Armor Lock: Its awesome. I love it, its a perfect "OH CRAP" button for anything coming at you from a decent distance. Activate close to enemies tho, and hope you've got backup coming.
Sword Base: I really like it, it really makes me think of the opening area on Halo 2, the space station. It was a nice jolt of nostalgia.
Assassination Animation: I don't know if its my controller, or the timing window is too short but I've accidentally gone into it when I just wanted to smash someone in the back of the head real quick.
Evade looks like its going to be ripe with abuse via Hammer / Sword. Then again, I'm probably wrong.
Really enjoying the feel of the gameplay so far, to me its like Halo but a bit different. I like it.
Now, slightly offtopic: In the Legendary Edition of Reach, does anyone know what the Noble Team statue is supposed to be made out of?