Pic Stitch is notable because its a highly rated app in the iOS app store, as pointed out by Microsoft's Joe Belfiore in this tweet. In iTunes in the US the app is currently ranked in 35th place and so its arrival on Windows Phone is one further step along the app gap road. While the app is well implemented and the benefits of familiarity for switching users should not be under estimated, it is also fair to say there are plenty of similar apps already in the Windows Phone Store.
If you're looking to create multi-photo frames or collages one of our favourite apps is the free JoyEye Multi-Lens, a photography app that includes both multi lens, support for creation picture collages (2-9 grids, 15 different themed backgrounds), filters, and social sharing.
Windows Phone Store description:
Quickly combine multiple photos into one beautifully framed picture. Pic Stitch packs a simple design with a powerful editor to give you everything you could possibly want to make your photo's simply amazing.
Share your masterpiece with all your family and friends with tons of in-app sharing options. Use Pic Stitch to create a before-and-after sequence, combine great photos of each of your kids
Pic Stitch, which is currently only available for Windows Phone 8, can be downloaded from the Windows Phone Store. The apps costs £1.29 / $1.49 / €1.49; no trial is available.