It's too early to get excited, but I'm definitely interested.
Retro-Bit's latest Super Retro-Cade unit is getting mostly good reviews. And as a company, they seem willing to improve their products based on feedback from their customers. So, in that respect, they're a cut above AtGames.
My main concern is that I don't believe the current gen of mobile phone SOCs really has the horsepower to emulate a Dreamcast satisfactorily. So I'm not sure how they could pull it off from a technical perspective, unless they're somehow able to take advantage of SEGA's inside knowledge of the Dreamcast's chipset, or the games' source code.