Games like Sonic 2 and Sonic Spinball were originally released on the Genesis and included in the Mega collection, so perhaps Sega wanted to release all things Sonic to clean out the closet. If you wanted to know why the Game Gear didn’t sell so well, this will give you a good idea. The graphics are horrible and the speed is reminiscent of playing a game that requires a Pentium 4 on a 486. You can play the games in the original aspect ratio of the Game Gear or in a full screen mode, but I just recommend you don’t play them at all.
I remember the Sonic Spinball of the Genesis, and the whole idea of the game was relaying the sense of "Sonic Speed." You do not get that sense of speed in the Game Gear version of the game.
Sega did included two more bonus games in the Sonic Gems collection – after you’ve played the game for 5 hours and 7 hours, Vectorman 1 and Vectorman 2 become playable. As we all know, an all inclusive Sonic Collection wouldn’t be complete without Vectorman. Apparently Vectorman won the "random Genesis roulette" game for inclusion here (Sonic Mega Collection had Comix Zone and Flicky).
While the games have nothing to do with Sonic, they do have everything to do with great old school gameplay and are still fun to play.
Other extras on the disc include the original instruction manuals and a "museum" where you see various artwork and illustrations. It’s a nice added touch.
Overall, for $29.99, it’s not a bad deal to get 3 "A" tier games, 2 "B" tier games and a lot of junky Game Gear games. However, if you’ve already played them, it’s not really worth a purchase unless there’s some hazing rule that requires you to get every Sonic game ever made.