It is a miniPC with a ton of Atari classics built-in. I think the large Atari collection is actually a big bonus, considering it's 2600 and arcade versions. Apparently the system can even run Steam Linux titles that meet the system's mid-grade specs. It's actually not a bad price for the hardware, assuming they manage to stick to the price AND the proposed specs. But you kinda have to want that particular hardware for it to make sense. At least it is keyboard and mouse-ready right out of the box. No futzing required.
In my opinion, there's not much pre-famicom worth playing. I mean it was amusing for the time, but the jump in innovation and polish from an Atari 2600 to a Famicom is a huge gap. Plus the fact that it was largely a cash grab, with everyone tweaking successful formulas ad nauseum instead of innovating (the same could be said now, but there was so much less to work with back then)
Early PC games can still be playable, like stuff for the Apple II, because some of them have fundamentally great design. But most Atari 2600 titles are a bit too basic. But not all. There are still some fun ones in there that hold up OK.