It's hard to really determine how I feel about such a thing.
On the one hand, Illumination is not a bad animation studio by any means, and they are gonna be overseen by Shigi which hopefully means there should be some semblance of direction that Nintendo can agree on.
On the other hand, Mario is often portrayed as such a non-character in his own games. He rarely shows any form of emotional expression that the player doesn't directly dictate which makes him kind of a blank slate if he had to stand on his own merits.
Also Mario generally doesn't talk beyond the occasional itaianesse noises, so the movie would be stuck making the rather hard choice between leaving him as a mostly mute main character who'd have to use only body language/have others speak for him, or give him a full speaking role which might sound off-putting to most people who are used to him not speaking. Either of these make for trouble given he's (likely) gonna be the main character
Still though Nintendo is currently riding off the overwhelmingly positive success of Mario Odyssey, so they aren't wrong to try and take advantage of the (larger than usual even by most Mario titles) hype.
Ultimately I guess we will have to wait and see to see how this will turn out.
Here's to hoping for the best given that if a video game movie staring the most popular video game character ever doesn't succeed, then no video game movie will EVER succeed.