I think they're okay but get too much hype like the Shield, but I do like the room inside the trigger, makes it handy if you're wearing gloves and need to use it.
I've only had to work on one, guys put about 800 rounds through it and since Ruger doesn't polish the feedramp on the LC9 and with the wear on the spring it got a little sluggish in cycling so polishing the feedramp real well helped it run pretty slick again.
The takedown feature is kind of a neat idea, but if you're not used to it you can mar up some plastic. Has that little "gate" covering the takedown pin so it doesn't walk out while shooting, but if you're not used to pushing that down then you can mar the frame or gate a bit until it occurs to you that it slides down.
For a double action polymer pocket gun, I'd say they're okay. Not that big into polymer though. I do admit I like the frame on the Sig 290, that has a lot of positive grip, but the trigger once again is a little long but you can stage it.
Ruger had a recall on LC9s about 8 months ago, that's when no one had them for about 3 months. They had a batch of firing pins get over-hard in the heat treat and and they ran the risk of breaking if shot a lot, but none of those pistols made it out on the market if I remember right, they found out about the problem when they were still at distributors.