I have to admit I have yet to use the Perfect Shot which is the golden standard of wii gun shells so I dont know how this compares. However, I found the Rabbid plunger gun to be an exceptional accessory. It felt just a tad bit top heavy, but I got used to this very quickly. The gun shell allows for use of the wiimote (sans the rubber jacket and wristband) and the nunchuck (which has to be held in your other hand) and works well with all of the zapper compatible games I've tried it with. The gun feels comfortable and does indeed make shooting games more fun (the only exception being the slow paced FPS minigames in Rabbids TV Party).
If you have the rabbid games, or a looking for a gun shell with some personality I cannot recommend this enough. It functions exceptionally, and feels great.