I found it fairly disappointing. I didn't attempt to analyze the reasons to the extent that this writer at National Review does, so I'm not sure whether I'd agree with him in every detail. But overall, yes. It's basically just a monster movie, without the character interest and deeper emotional reach of Series 1, and a less believable plot. A couple of unconvincing and out-of-place gestures toward pop culture's LGBT obsession didn't help.
Reportedly there will be a Series 4. Given that most of those who loved Series 1 were disappointed in 2, and more so in 3 (or at least that was my impression), I don't have high expectations for any further stories. But it's not unheard for a show to reverse a downhill slide, so I won't give up entirely.