I didn't play GX, but a friend of mine, who usually has good taste did, and he really enjoyed it. What specifically did you find bad about it?
If your friend can get past the Casino stage in story mode then he is a greater gamer than me. The best I could ever do on that was third place, and I only managed it once or twice. The problem of course is that its only the third or fourth stage in the story mode, and you absolutely must drive a perfect race to finish first and move on to the next story chapter. Some asshole knocks you into the wall? Better luck next time loser, because you just lost your chance to clear the stage. I remember I once I got to the end without hitting the wall once and with no serious bumps from other cars, and of course I still finished third. Why? Because you gotta use Captain Blue's vastly inferior vehicle, too, so better machines like White Cat and Astro Robin often blow right past you every time on their way to victory lane. Luck seems to play way too big a part in this mode.
That and the normal racing mode is far too easy compared to the SNES, and N64 versions. Combining the too-easy racing mode with the too-hard story mode leaves no middle ground that has a nice, enjoyable balance.
I've ignored the handheld F-Zero games personally, and never really considered them major branches of the franchise, they just strike me as negligible offshoots.
GP Legend is the only handheld one I've played. Maximum Velocity is older, indicating GP Legend should be the superior game. However, it plays like a poor port of the SNES version, with more garbage on the track just to irritate you. And they tried to make it tie in with the short-lived Saturday morning cartoon, so it just sucked donkeys story-wise.
I think Nintendo turned this one over to Sunsoft to develop, proving that the third party developers usually make a mess of things where Nintendo's first party franchises are concerned.
