we haven't had any problems with our Rock Band equipment (from FS), and we've been using it rather extensively for the past week. the three big things we've noticed are:
1. the bass pedal for the drum is designed poorly,
2. the drum pads make a LOT of noise when hit, and
3. the Stratocaster guitar works fine, but the strum bar is weak sauce
here's a few things we've done for each:
1. the issue with the drum's bass pedal is that there aren't enough pads on the bottom part, so the weight of the foot isn't distributed evenly and it will bend and eventually break when used enough. we installed a few extra pads with some screws and our pedal no longer shows signs of bending when pressed from any angle. (i can take a few pictures if anyone really needs them)
2. the drum pads are noisy, so we recommend making some noise-dampening pads like some folks have been doing with foam rubber and felt. they do cut down on the noise quite a bit, and they're quite cheap to make (8 bucks, if you don't get the pricey Circle Cutter). these can also be bought from a few sites and eBay sellers, but i honestly believe they're easy enough for anyone to make at home for much less. the instructions are here:
http://generationgamerz.com/v2/insight/time-for-rock-band-arts-crafts.php
3. the Strat is a decent enough controller and i haven't had any issues with the strum bar as many folks seem to, but the lack of a "click" when strumming throws me off. this weekend, i'm going to crack it open and modify the innards as Mr. Ben Heck did on his site. this probably will void your warranty, although there's no "VOID" sticker on the back like GH3's Les Paul:
http://benheck.com/12-10-2007/how-to-improve-the-rock-band-guitar-strummer
so, there you go, a few things we've done to extend the life of our fake instruments and have some more fun with them.
Edit: spelling mistakes, haha