Although after-market accessories can work and fit very well in most cases, it has been my experience that few accessories work or fit as well as those provided my the manufacturer itself.
This laser fits the P22 perfectly -- and it would be impossible to have an easier installation.
I've taken it shooting twice now; it was quite accurate right out of the box, but was easy to "zero" using the available adjustments.
It's easy to be skeptical about lower-priced accessories, but in the case of this Walther laser sight for the P22, it looks and performs exactly as advertised.
Pros: Perfect fit, very easy to use and accurate -- right out of the box
This review was written in the old system and had content requirements that are different than reviews written today.