I have two of them on related machines that I am starting up now.
They're very similar to the other CompactLogix controllers, really. If you're using RSLogix 5000 v20 with POINT I/O, there's hardly any difference with any other controller.
Connection with USB was very straightforward, and the firmware load was easy to do. I've been connected over Ethernet ever since and it works fine.
The principal surprises I've had were due to the relatively low-power POINT I/O scanner on the local bus. If you want to use analog or specialty modules, the scantimes can get relatively long. Allow 20 ms for each analog or specialty module.
The SD card nonvolatile memory is nice; I have three devices in the control system that use SD memory, so I have the backup files for the other two loaded onto the same SD card that stays in the CompactLogix slot.
Like many OEMs who build small machines and use the A-B portfolio, CompactLogix and MicroLogix 1100/1400 are our usual platforms. I'm going to strongly consider the L16 and L18 controllers for systems that don't need the I/O features (relay/DC mix, high-speed options) or serial ports (RS-232, RS-485) of the MicroLogix. I can make up the difference in hardware cost with efficiency of programming, as I'm a better and faster programmer (and have more libraries of reusable code) in RSLogix 5000.