Got to test this one today, wasn't too impressed. The loading times were pretty bad (but I suppose inevitable from a technical point of view, these aren't ROM cartridges after all), the number keys work poorly as in-game buttons and the framerate of Tomb Raider (the game on display) was choppy. The telephone part's OS also seemed unintuitive but after going back and forth in the menus for a while I did manage to get the game running, which seems to be more than most manage.
But! However! As I've said in other places, this would make a great platform for vertically scrolling shmups. The screen has the right format (and seemed quite allright, especially compared to the GBA's) and the two raised number keys would work fine as gun and bomb buttons. Ah well, one can always hope..