I was a bit too late to give thoughts on RC1 but here goes on the final version:
I am using Linux mint 11 Gnome 32bit
*The Grand Prix progress bar is listed vertically down the screen without any way to scroll through it. Is that just me? Quite pointless in this setup
*Hacienda...I miss the 3 nitros at the top of the ramp. I assume you realised you were making it too easy for us.

*Auto rescue kicks in too quickly after crashing into a wall, especially noticable and distracting in Snow peak. I can understand an automatic kick-in after going over a cliff or something, but not crashing into a wall.
*Muffins of Death dont seem to be as guided as before. Seem to be lobbed over karts a lot more than before.
*Fort Magma is now way too easy- Previous version was more enjoyable for me.
*Zen Garden: nice track but too mant presents makes it too chaotic.
*I dont like the bouncing ball at all - too random
*Subsea - current version too easy (even with the glare on my screen)
QUESTIONS:
Should I delete a particular file or files after using RC1 to notice more of a difference between RC1 and the final version. I notice that some karts I added on are in this version when I play it but dont know if that should be the case. I didnt have to complete challenges which suited me but am wondering if I am not seeing the "new" version because I was previously running RC1.
I assume I started with version 6 a couple of years back. I remember 1 track which consisted of driving through a living room and out into the garden. Anyone know of a still active Linux repo which may have this version of STK...or where else Icould get a chance to play it again?
Suggestions for the future:
Allow players to make their own Grand Prix by ticking or dragging tracks into their Grand Prix setup. Maye even include the same tracks more than once?
Highscores: include AI karts in the hiscore tables.After each race,show a high score table for that track and also have a seperate section in the main menu like "Stats" where this could show up.
Other stats: at the end of a GP, show a grid with the player's position in each race,and position in the league table after same race.
Save global stats per user like total races , races won, etc... you get the idea.
Cheers and keep up the good work.