The P22 is a Umarex product. Umarex is the parent company of Walther; its primary line and area of expertise is air guns. Uarex began its association with Walther in the early 1990s and has been the dirving force behind the P22. The P99 and the PPS, in comparison, are both Walther products and superior in every way.
This is not to knock the P22. Many folks love it and find it a great range companion, despite the pot-metal construction of its slide and the overall throw-away, disposable nature of the design (when it breaks, toss it ... much like a plastic Bic lighter). But it's not a Walther.
Again, try a Ruger, Browning, Colt, or a real Walther: the PP or PPK.