The USP is a large frame pistol with a sizeable grip. It is accurate/reliable and well made.
The number of trigger options and the ambi mag release allow it to be adapated to a large number of shooters.
It is not and should not be viewed as a replacement for a custom 1911 .45 pistol. The USP does offer a large number of technical innovations over the 1911 and it's competitors and it is a design that is more tolerant of varied environments and climates.
It is an accurate, reliable, duty class sidearm suitable for a wide variety of uses and applications.
It is well made and should outlast the average owner.
IMO the custom models are not really custom and should be avoided unless you can make apurchase at a good price.
I would not compare it to the SOCOM as the SOCOM is an offensive design versus a defensive design in the USP and the SOCOM suffers from multiple design parameters that make it an excellent offensive pistol such as size and platform design that make it an awful defensive or concealed carry pistol.
I have a USP 45. I like it because the grip and controls remind me of a 1911. Since I'm used to a crisp single action, the USP's trigger action was horrible. I since had it tuned by Teddy Jacobson. My USP is accurate and reliable.
You need a medium to large hand to shoot this pistol. That said, I like mine a lot. It has a light recoil for a .45. It has 2 recoil springs. It is a long lasting and very accurate pistol. I have a Jarvis Custom Barrel with conventional rifleing I use in mine on and off. It is tactical length, without threads, and very accurate with Remmington match SWC. This is a pistol that can evolve to what ever you want: Longer barrel? Match trigger? Diffrent sights? It is no harder to hide than your full sized 1911-A1, both are larger than a Kahr or my P7-M8. I cary the .45 in the winter under more clothing. Teddy Jacobson can fix the trigger. I'am another Old Guy.