I'd give them a decent 7. I think they put a lot more work in the design this time and while not the best, I think of it as : great idea, poor execution. Like someone else said, the fossils were a great idea but the lack of storyline like "go do this and that to get X item, after you get items X,Y,Z you may start to find fossils around the map, bla bla *insert generic bad guys that stole these fossils*", makes it a bit of a downer. It was DECENT both from design and gameplay P.O.V.
At the end of the day, this is the only pokemon game where I vouched I'll fill my pokedex.
In Pokemon Let's GO where I have even the physical pokeball-controller, I finished the game and had less that 3 boxes of pokemon filled (with tons of dupes). #onixLove