I like the turret in pve. The sticky bomb is kinda shit to use unless you have high ground and can see the radius better. The turret pulls agro if anything else. It was pretty useful on medical mission hard mode.
It holds aggro but not as well as I think it should. I can pull aggro off it with 1 shot and I'm using a pretty good suppressor. I think it works better in groups of two as enemies have a hard time focusing on one or the other. It's freaking hilarious when four turrets are down, enemies go nuts.