Plays like a VERY fun "Mass Effect in the 50s" squad-based tactical shooter (not a true X-COM title=no prob)
I can describe the combat in a single sentence: THIS IS INDEED THE MASS EFFECT EXPANSION YOU WERE LOOKING FOR; play on Commander difficulty
You can always lower the difficulty later if it's too hard, and the autosave system creates a new file at the beginning of every major mission so it's very easy to go back and replay anything you want.
Exploring the base, with its NPC conversation branches & side missions, is pretty much also exactly like a Mass Effect title. Although there are a few rough edges, this makes for a nice break between the entirely combat-focused missions.
If you like shlocky 50s-themed (despite the 1962 date in the intro) alien themes, ME's squad combat, "X-COM-themed" old-school aliens, and (most importantly) if you want something that's just a little different than anything else you're playing this year...
Then this game is definitely worth the money.