There are a few technical issues (mutants getting stuck in walls for one) but all in all, it's a solidly made game. The few issues aside, however, you'd be hard-pressed to find a more enjoyable way to spend an afternoon.
The whole thing is very well built. Sure it's plastic, but it's not cheap feeling–it actually feels very solid. And with the Wii Remote inserted, it has the perfect amount of heft. The Nyko Perfect Shot is everything the Wii Zapper should have been, and more. There's even a pass-through for the extension port on the bottom of the handle, allowing you to plug in your nunchuk.