When I managed a gun store for a couple years in the late Eighties between college and law school, these were still popular enough (mostly as backups for LEOs) that we kept them in stock. They were pretty nice guns. The downsides of spare magazines and recoil buffers have been mentioned.
One that has not been mentioned yet is the relatively brittle nature of their firing pins: do NOT dry-fire these (or the Star BM/BKMs, either), or you are likely to find yourself in scouring the internet trying to buy a replacement pin.
Because of the parts replacement issues, I haven't given them any thought since the Nineties when Star went out of business. On the whole, I'd opine there are much better and more practical modern arms that fill this compact, light .45 ACP niche (I note I'm wearing a Glock 36 as I type this, and the Shield that was mentioned is a dandy). Recoil on these polymer guns is somewhat less than on the Al-framed Star PD, too, but a .45 ACP probably isn't an issue unless you have grip frailty or reasonably serious arthritis.