I very much enjoyed the Titanfall beta. I can't wait for the actual game to come out.
It adds a lot to your standard FPS, with so many different ways to play, often changing several times during a match.
I'm hoping the final product has a co-op mode. Also, I do think that Respawn missed an opportunity to make an original, creative single-player campaign. I'm interested to see how they weave single-player aspects into the multiplayer.