So I've been playing the beta a little and I've noticed a few things about it.
Glitches:
Sometimes the Xenonauts are able to run through solid walls. It seems to have something to do with fog of war, occasionally the pathing doesn't correct after the route is revealed as impassable and the guy just goes through.
AI issues:
Enemies never shoot at Xenonauts on their own turn. They only ever take reaction shots at my guys, and chase civilians aggressively. If there are no civilians to shoot at, they'll run around aimlessly, flee, take cover -- anything but shoot. Even if I walk right up to an enemy this doesn't change. The alien will either run away or just stay put and do nothing, letting me shoot it freely.
Local forces will happily shoot Xenonauts in the back if they're between a local and an alien. I had a farmer shoot one of my guys in the back no less than four times in a single turn, trying to kill an unconscious alien I'd knocked out the previous round. He continued trying to shoot it for the rest of the mission.
Crashes:
Each of my two campaigns ended prematurely after reaching a state where finishing a ground combat mission caused the game to crash after receiving the soldier upgrades. The first time this was after 20+ missions in about two months, the second after 10+ missions in a little over a month. It would crash each time even after I replayed it from the mission start autosave.
The first time I loaded a save from before the mission started, played it through and got it to work, but after that it just started crashing at random points in the base menus so I gave up.