I got this game when it came out, and played up to the alien base mission before I put it down because the bugs were killing me (bugs as in glitches in the game, not the Chryssalids - zing). Now, I'm back and started a new game to play through the DLC. Both times, I thought I had a pretty badass XCOM team, but boy, once you attack that alien base, the aliens stop playing around and this game gets tough.
For some reason, I like the game more now. I like that halfway through it challenges your established strategy.