I have experienced no lag so far or other issues. The matchmaking is pretty good but definitely can be improved and optimized as far as connecting matches faster. I'm sure as beta finishes and game gets closer to release it will be improved. It also has classic modes like Juggernaut in beta as well. Powerhouse map was fun for small to mid-size matches. Overall, it's classic Halo multi-player with some new tweaks, weapons, and new modes.
So what do you think of beta so far?