I always check out what's included in the limited, special, etc. editions before I reserve, and it's typically those games that I reserve and never the others. I've only reserved three games of the such at this point.
Halo 3 Limited Edition (Not legendary) Included an extra "art" book with just some race profiles and other junk, some themes and icons, and a DVD. all in a two sided metal case. I wasn't impressed, but it was only something like ten dollars more american.
GTA IV Special Edition came with a, as stated above a small, but useful duffle bag, Art book, sound track, key chain, the game of course and all of it in a steel lockbox, which is surprisingly more useful than I first had figured it would be. I traded some fames in towards it, ones my roommates at school had persuaded me into buying (NHL 08, Madden 08, they were hockey players, and the worst lot to boot). So instead of ninety it came down to forty, and that included the strategy guide i picked up.
The third game I've recently reserved is SCIV. It comes with the game of course, along with a T-Shirt (Black for the PS3 and white for the Xbox with their respective cover art characters), an art book, a tournament kit which apparently is just a glorified reusable blank bracket card, or so I've heard, a large metal tin to throw it all in, but more importantly it comes with a redeemable code for exclusive content for the game such as weapons and/or armor and clothing. for eighty bucks I thought it was worth it, and the only cost to reserve it was ten bucks which goes towards the over all purchase of the game. Come july I'll grab it for the remaining seventy