The Sega Nomad was a good idea in theory - a proper hand-held console letting you play all those great Mega Drive games on the go. However, it had several problems that led to its downfall. For starters, it looks like, and probably as heavy as, a brick. Doesn't make it very portable. Second, it was a power whore. Limited battery time compared to the Game Boy, and Ni-Cd batteries were a no go. Finally, it was released at a time when the 16-bit era was being replaced with the 32-bit consoles (Sega Saturn, Sony Playstation, Nintendo 64). People were looking towards new and better things and even if the Nomad had succeeded, it wouldn't have brought in many sales. The fact it bombed pretty much sealed its fate.
Having said all that, I will probably get one in the future, add it to the gaming museum I have going on here.
I think they are pretty neat. In my house we collect old retro games and consoles. Luckily we got a great deal on one. $25 for one boxed with the rechargable battery pak, adapter, all the manuals, and 2 games.
My boyfriend actually plays it pretty often despite it mostly went to his collection.
It just didn't come out at a good time and definitely does love batteries.