Track editor is simple what's to read about. Haven't delved too much into it yet but it gives you a lot of freedom and you can create some massive tracks, i've made one 3 minute one so far. Handling felt a bit weird at first after playing the console one so much, but its very fun. Braking points seem dead on realistic but the car slides around a bit more. Dpad isn't as big a problem as I thought it'd be, it just gets annoying sometimes trying to straighten the car up on straights and getting through fast long turns smoothly, it can disrupt your flow. One bad thing about it compared to the PS2 version is the AI is a bit wild and weird, the actual racing / overtaking is a bit lame, and the damage is a lot more forgiving.
It's pretty fantastic how much they've squeezed into this little cartridge.