Just recently received 2 Perfect Shots from Amazon for $13 a piece. I own RE: UC, Ghost Squad (GS), Link's Crossbow Training (LCT), and the Wii Zapper. Simply put, the Perfect Shot is way better than the Zapper (e.g. accuracy) and in some ways better than the Wiimote (e.g. realism). Below are my impressions (pro/con format) for those who are undecided.
Perfect Shot:
+ On RE: UC, reloading (flicking the nunchuk) and knifing (hold Z and flicking the nunchuk) is much better w/ Zapper controls than with Wiimote's.
- On RE: UC, QTEs (quicktime events) are harder due to the Nunchuk's crappier accelerometer. I never fail with Wiimote controls
+ On GS, hands down this is the best control setup, especially w/o a reticle. Realistic gun and dual-wielding FTW
* Haven't tried it on LCT
Zapper:
- On RE: UC, it's a chore on the arms b/c too much waggle is needed to reload or do QTEs (quicktime events). Worst control method of the 3
- On GS, it doesn't feel as natural as the Perfect Shot with or without reticles. The controls aren't horrible or anything, they're just meh
+ On LCT, no complaints. It works better for me than the Wiimote. This is my personal taste, though.
Wiimote:
+ On RE: UC, this is the best control method (slightly better than Perfect Shot's). QTE controls and head shotting zombies work flawlessly for experts
* Haven't tried on GS
- On LCT, prefer Zapper over Wiimote.