I'm not entirely sold on its style. It's a little too Sonic Adventure to me.
It's not like Sonic Adventure at all. The only reason people think that is the somewhat realistic human NPC's in one zone. It helps that Mario is using it as a fun, weird zone and not the JRPG to be taken seriously shit in SA.
The issues with SA were:
-Really sucky controls, even for the time [Odyssey looks like it controls just fine]
-Throwing in lots of new characters that no one cared about [So far Odyssey has shown us Mario, Peach, Bowser, and a hat]
-Most of the "highlight reel" sections were essentially on-rails [I highly doubt this will be an issue with Odyssey]
-Starting to focus too much on story [Again, don't see this being an issue with Odyssey]
So, yeah, I'm not seeing the comparisons to Sonic Adventure at all, really.