If you haven't played this yet, what are you waiting for?
I've had the game since Christmas, and I'm on my second guitar and my second drum foot pedal. The guitar strum bar stopped registering, and the plastic foot pedal eventually just snapped. I've seen several complaints by players who have had to deal with even more returns than I have, but I truly think that the equipment problems are becoming fewer and farther between. And the return policy can't be beat. You make a claim, they put a temporary hold on your credit card (they don't charge you), they ship you a replacement component, you return the broken component in the same box with pre-paid shipping. It doesn't get any easier.
So, since the equipment issues are overcome easily enough, let's talk about the gameplay. I'm on the XBOX 360 version, and everyone that I invite over to play this game is utterly amazed at the detail of the game and immediately addicted (to the point where I've had trouble getting them to leave my house). As has been written time and time again, the heart of this game is in the multiplayer modes. The solo tours are fun, and they're incredibly important for unlocking bonus songs and learning your instrument of choice. However, you're not going to sit there and play by yourself indefinitely. Get some friends over and play as a band in the World Tour mode, and you'll find yourself pushing the limits of your musical abilities in no time.
The things I love most about this game -
I'm learning how to play real drum patterns, even though some of the pads pull double duty (toms and cymbals are often simulated by the same pad). The original list of 58 songs is pretty incredible. Sure, there are some songs that I had never heard of, but there are also some epic tunes from the past 5 decades. Frequent downloadable content makes for an ever-expanding challenge, and the game is accessible for players with a wide range of musical abilities.
The not so great things about Rock Band -
Harmonix has been releasing 3 songs per week for download, which sounds great. Unfortunately, out of the 40-plus songs available for download at this point, I've only downloaded 10 of them. Harmonix has released some real crap, especially in late January and early February. The songs cost $2.00 a piece, so I'm not downloading everything they put out. I hope it gets better soon.
The biggest beef that I have with the game is the fan cap in the World Tour Mode. I was OK when I realized that our band couldn't progress past 260,000 fans on Medium difficulty. After all, Medium difficulty is the default starting point, so I understand the motivation to move up to Hard and Expert eventually. However, when I realized that the fan cap on Hard difficulty was only 600,000 fans, I was a bit distraught. Finding a drummer and a lead guitarist who can play more than a few songs on Expert at the same time is quite a challenge. I think a full band playing on Hard difficulty should be able to attract a few million fans, but the developers never asked me my opinion.
Overall, this game is incredible. They overmarketed and underdistributed to get things started this past holiday season, but I'm really very impressed with how they've handled the huge demand, the equipment returns, and the frequent DLC. Great game, great support - worth every penny!