I'm one of the original suckers who dropped $36 down for the game on GMG, then I threw down another $18 for the Season Pass there. Was hugely disappointed by the part of the campaign I've played, and still am, but the new patch has helped a bit. Last night I fired up the new Bug Hunt DLC, and I gotta say, it's a lot of fun. The maps play a lot like Black Ops zombie mode, money for kills/assists/wave clears, and then you unlock gates and activate suppression with it. They definitely have done some work on the alien AI, but they include waves of the Weylon soldiers here and there, and that kind of feels dumb, just like in the main campaign.
Overall, I'm enjoying it, played up to wave 26 with a group this morning, going to definitely jump back in since it's 25F and snowy here, good gaming weather.
If you have the main game and are looking for a reason to actually play it, Bug Hunt might be it.