I won't say I'm not concerned about how it'll play out towards the end game, but for the moment, the biggest gripe I have with it is the loading times. So far though, it's been a new take on a game I've really enjoyed. The new soldier class trees on the other hand, look to be really diverse with plenty of choices in them. There are new tech levels and Aliens to help combat this, but I'm a little worried how thats going to play out over 100+ missions. In the base game, you got new technologies and new enemies introduced at a reasonable rate that kept it inline, roughly, with your soliders XP gains.
I'm also a little worried about the pacing of the mod too. Having to manage the Haven's too seems like it'll get a little tedious towards the end too. Having Squads helps out tremendously, but there's still a lot you'll need to manage for your squads to get the most out of them. First of all it seems as though it's going to get obscene with all the micromanagement you'll need to do towards the end of the game. I do, however, have my concerns about it going forwards though. From what little of it I've been able to play so far, it's been a very fun experience.