Aside from Bug Hunt, I thought the Stasis Interrupted DLC campaign wasn't bad - it was certainly better than virtually all of the original campaign.
But in regards to Bug Hunt, I feel the following would have made it a better experience for me:
1) Keep the classic Alien skins throughout. I didn't like how after the first few waves, we got the bizarre horned carapaces on xenos for the rest of the game.
2) Have a boss fight at Wave 30. Ending the game with a battle against an Alien Queen would have made it a much more enjoyable conclusion than just killing "X" amount of enemies on the final wave.
3) Implement dedicated servers. As a game, A:CM might have enjoyed similar longevity for its multiplayer component as the last Aliens Vs Predator game did if Gearbox hadn't saddled it with that f**king horrible lobby-based matchmaking system. Hell, I'd probably STILL be booting up the game if I could find some active sessions running for Bug Hunt.