Reach's BTB is dreadful. Really bad.
If I was a BTB fan, I would be seriously annoyed at the maps on offer. But I like close and competitive 4v4, and I've come around to liking the maps for the most part (except for The Cage, because it's wretched, and Reflection and Boardwalk, because they're not well-managed), and loving Countdown (which is as good a 4v4 map as there is except for Lockout, Midship, Citadel, and The Pit, and I think I might like it more than The Pit, seriously), Zealot, and even Asylum in its bumpy and laggy state. And I think the gameplay is pretty fucking polished, on the whole. It helps that I have no general beef with AL, though individual instances can annoy me.
But whenever I play BTB (or Invasion Slayer) with friends, I feel less inclined to play the game as a whole. It's in a seriously bad way.