There are some great games that make it worthwhile. Most people pick up the sonic games, which are not very good.
Ouch, dude, come on... talk about subjective...
The 8-bit Sonic games aren't the same as the Genesis series, but they still hold their own. Inventive, large, challenging, and their music is just as competent as any other Sonic game... They're not objectively 'bad' just because you may happen to not like them 
Things falter a bit with the Drift games, Labyrinth, and Blast, but the standard "normal Sonic games" are as viable as any other 2D Sonic entry.
I could say the Wonderboy or Shinobi games are "not very good," but in reality, they're just not fun for me, I think they're boring. Ristar is just a copy of the Genesis version, admittedly quite playable, but still pointless if you've got it's bigger brother. Tempo Jr is very slow and plodding, I found it to be considerably dull compared to the first one on the 32X, both visually and the gameplay itself.
To be fair, everyone just has their own preferences, so it's really up to a new collector to do exactly what fauxshot here has done... put out some feelers and see what might be a good start. 
I use rechargeable batteries on mine... ...it is but it is between 6 and 10 hours. I would guess about 7.
you, sir, must be a wizard, because I've never gotten over 3 hours in my GG or Nomad before the battery light started yelling at me, and I've never had the machine last over 4 hours. I've technically had no reason to play either one in the last 15 years, so who knows, maybe new battery tech really does make a difference... but I'd be hard-pressed to believe it, and I'm not shelling out cash on batteries to test lol
I would argue that the Game Gear ports are not very good. The SMS Sonic game is great. The bridge zone music is iconic. But, I don't think the ports to GG were great besides the first one. That one is still good. But it is subjective. Every game out there is someone's favorite game.
Thank you for the Wizard comment.
Although, I can't take full credit for it. I just did some research on what other people did and realized that technology does improve over time. RetroGameTech on youtube got similar results with 7+ hours on the Nomad. The Game Gear generally seems to last longer for me than the Nomad. With no screen mod, I'd estimate my nomad gets around 6 and Game Gear seems to do better. But I have not fully tested it. I use the highest capacity NiMH batteries I could get. The capacity is much closer to Lithium Ion batteries than alkaline. These were just commercially available in 89 and did not become widely available well after that. So, it is fairly easy to see them get better results than the quoted battery life of the Game Gear in 1990/1991.
http://www.greenbatteries.com/battery-myths-vs-battery-facts-1/From the linked site: For example AA alkaline batteries typically have a capacity rating of over 2,500 mAh and AA NiMH batteries have rated capacities of only 1,200 to 1,900 mAh. But when it comes to actually powering an electronic device like a digital camera, the NiMH batteries will often run the device for three or four times as long.
