I've got a 9mm Shield with 420 rounds through it.
Reliability: It had one FTE in the first 100 rounds with 115 gr S&B range ammo, and another in the second hundred rounds with Magtech 115 gr range ammo. I chalk it up to fairly mild loads in a new gun. The last hundred rounds I put through it were also the Magtech, and ran flawlessly.
These could have been due to limpwristing, but a) I don't do that, and b) every range session I alternate between two-handed, and both strong and weak hand unsupported, and it's never shown any hiccups with the weak hand. I don't think it's particularly prone to limp wristing failures.
The trigger was very rough when new. The trigger bar engages a plunger, and the channel the plunger rides in must have a bur on it. Initially, it was so rough that it would catch there right before breaking and take at least twenty pounds to break. I discussed the issue with a local gunsmith with a very good reputation, and he said just to keep shooting and cleaning it and it'd work itself out. It's pretty much worked out at this point. I suspect it'll be very smooth in a few hundred rounds. It's more than adequate as it sits now.
The gun has very thin grips, but isn't especially light. It's top heavy, but that doesn't seem to affect the handling much in actual use. I've put a Hogue Hand-All Jr grip sleeve on it, and it feels much better.
Weight-wise, with the Hand-Alls installed, it's 1.51 lbs with the 7 round mag and 1.56 lbs with the 8 round mag, loaded. (Federal 124 gr Hydrashocks -- I know, not the best, but all I could find at the time.) Holstered in a Sticky holster, it comes to 1.626 lbs with the 8 round, loaded.
So, it's not the lightest gun. IMO, it's great for IWB carry, not so much for pocket carry, though I do carry it in a jacket pocket. It's definitely in the "so small you'll forget you're carrying it" category.
Accuracy is outstanding, once the trigger is broken in. (If you really hate the trigger, Apex makes a trigger kit that improves it considerably. The smith I mentioned above doesn't believe the Shield needs one, though, and I agree. The design seems very sound, mine just had an issue with the finish, which isn't surprising at this price point.)
As for the yellow lever to push when taking it down. You don't have to use it, and can pull the trigger same as a Glock, instead. This just gives you an option that doesn't involve pulling the trigger. Which is not a bad thing, IMO. Youtube has a takedown video or two that shows both methods. Both are easy enough. This is a very easy gun to maintain.
I really don't like the sights. Lots of reviewers seem to love them. I find the front sight a PITA to acquire in lower light due to the dot being very dull and smaller in comparison to the rear dots. They'd have been better off to leave the dots off altogether IMO. Fortunately, there are several aftermarket sights available. I'll probably put the XS big dots on it when I get the extra funds. Of course, my eyes are starting to hit middle age, so this may not be an issue for a lot of folks.
I haven't experienced any of the problems listed in the OP, aside from the two FTEs that haven't recurred.