There are plenty of fantastic Game Gear games. Finding them may be quite a challenge, however.
Teddy Boy, Wonder Boy In Monster Land/World, Sonic Chaos, Jurrassic Park, Tempo JR, Ristar, Powerstrike, Itchy & Scratchy Mini Golf, Golden Axe Warrior, Panzer Dragoon Mini, Psychic World, Bubble Bobble... Plenty.
I myself have never owned a Game Gear, but one of my best friends did many a year ago. Good times. You may want to invest in an AC adaptor, though.
I've learned the majority of its good games via the Master System (90% of Game Gear games were also on Master System) and good ol' emulation.
And if you find a TV Tuner, QUICKLY buy it. It's become one the hardest things to ever find on Game Gear now. Basically, it let you watch TV on your Game Gear. Full colour.