The guide recoil spring is not contained or attached to the guide rod, so when you take the slide off it tends to be a bit of a pain in the arse to reassemble. Walther sends a plastic rod which has the sole purpose of guiding the spring back onto the guide rod when reattaching the slide to the body.
Also, when you decide to take apart the trigger assembly there are a couple of teeny-tiny springs that tend to fly out because they aren't attached. It is recommended that you disassemble the entire gun in a baggy to help contain the event.
I own a Walther p22 and I am not impressed with its engineering; however it is the coolest looking .22 plinker I can find
I run federal bulk pack through both of my p-22s with zero problems.
Others that are far more knowledgeable than me with them suggest that you run about 500 rounds of high velocity ammo like CCI Mini-Mags through it before using standard velocity ammo to help break the gun in.
Get both!
You can never have too many .22 pistols in my opinion.
The P22 has to be my favorite though, it comes in many colors (stainless slide, camo, pink etc ...)