I'm a 1911 45ACP type guy and all my carry guns for the last 15 years have been 1911s. But I also have osteoarthritis in my back. The weight of my 1911s gives my back a fit at times and I wasn't able to carry much of the time. Not something I liked!! So last Sept. I wandered into a new gun store while on vacation and found a Shield 9mm with a thumb safety. Handled it, did a couple of dry fires, and the trigger wasn't too horrible. It had about an 8lb pull, later verified with my digital trigger gauge as 8 to 9.25lbs pull. I liked the weight and size a lot, so I bought it. When I got home I started reading the S&W forums for the M&P pistols. I wound up ordering a Apex duty/carry kit and installing it which made a huge difference in the trigger pull and smoothness. After about 300 more rounds of ammo I decided to order the Apex trigger and installed it. That brought the trigger pull down to 4lbs 4 oz very consistently from shot to shot with a lot less takeup and overtravel. My 1911s are set for 4lb trigger pulls and that's the way I like my triggers. All my 1911a have thumb safeties so I'm used to them and find the one on the Shield to be very decent and easy to use. I won't have a defensive pistol with out a thumb safety, but that just me. So now when my back gives me a fit I switch to the Shield. I also installed some Talon Granulate grips on it, fantastic! I consistently shoot 3 in groups at 21 to 35 ft, my normal practice ranges. I also put some Ameriglo Orange/Green night sights on it, love them.
Pros: Very accurate, light weight, small and very easy to conceal, 100% reliable with everything I've used in it. and it doesn't hurt my back!!!
Cons: I don't really have any, other than my preference for a much better trigger. But that was my choice and the gun was perfectly useable out of the box. I just do better with less trigger pull weight.
All of my 1911s have had trigger jobs done on them also. I learned about 12 years ago how to do safe and effective 1911 trigger jobs.