Never played Diddy Kong Racing(I didn't even know N64 existed when I was a little kid!), but I've watched some reviews on it before. Seems like quite the wacky game, but so were the 90s I guess. 

In retrospect, you're right, Grand Prix Mode should be kept alongside a new story mode. I loved collecting 3 stars on all tracks in the Grand Prix. But I really really want to see a story mode, but they would've told us by now already if they were going to do this. Unless they want to really surprise us.

Also looking forward to see what new weapons will be in the game. And when they're going to troll us with a trailer that shows the blue shell. They've been trying to keep that one secret for some reason. :P

The majority of the people seem to think the game will score 90%+ which makes me believe this is the most hyped Mario Kart to date. Could be wrong though, wasn't around in the old days. 

Metacritic quotation: "Bland and uncreative track designs." - Gamespot

Mummelmann said:

6/10 Gamespot, "too similar to previous iterations, lack of innovation, so-so level design".

Call of Duty 125: Black Ghosts at War with Big Red: 9/10, "outstanding stuff, lots of sob's yelling on Live, glossy visuals,

never get sick of this shit".

Metacritic quotation: "Bland and uncreative track designs." - Gamespot

Between 80-85, I think.
Professional reviewers will deduct points for it being too kiddy, too colourful, not sporting 4k tesselation teraflops, nor featuring a sandbox overworld set in 22nd century New York City. The lack of a deep and dark mature storyline will be a point of complaints as well. Also, Nintendo is stupid 'cuz they made MK instead of F-Zero, which would've been smarter.

I wouldn't put it past them.

Also, deducted points for being more of the same; racing in karts on tracks. And half of them are even re-used ones from previous games! So lazy. I mean, just look at this track lifted straight from the SNES Kart:

You can still see that track comes from a SNES game, bad graphics! 

That pic of Toad reminded me that I want to have the option to have different colored Toads(and Toadettes). Not as brand new characters obviously, but as reskins. And Toadette reminds me of nothing! In what game(s) has she actually starred? I can't remember ever seeing her besides in spin-off titles. It's a pity she wasn't playable in Super Mario 3D World as an alternative skin of Toad.