I'm cleaning up after finishing the game and I'm just blasting through the levels. Initially, I sympathised with the claims of levels being too long and boxes being consistently too hidden (and in some cases, they are and I've had to look at a guide for more than a couple), but I'm starting to lean the other way now. Once you know where they are, this feels just like the original trilogy, and the level length drops to 3 to 4 minutes grabbing everything towards the middle of the game. That might change once I reach the very late game, but I'm soaring through some of these earlier levels and sections that gave me trouble, so I doubt it. By the time you've finished mopping up the gems on both normal and N. Verted mode, you're well prepared to grab the N. Sanely Perfect relic, often picking it up during your N. Verted run.
I'm loving this game. There are some issues which others have touched upon, with most importantly the controls/hitboxes for Polar and Shnurgle (yeah, that's its name), a small number of hidden boxes on a first runthrough and having skins locked behind a set number of gems per level rather than in total, but they can all be tweaked if need be. Someone earlier in this thread also brought up a lack of cooldown and I can agree. The bonuses used to be a chill pit stop for you to get some extra lives, but now they're all fiendish puzzles and that can tire you out if you're playing nonstop.
I enjoyed the story and cutscenes too. The cutscene at the start of Out For Launch had me laughing hard, and this is easily the best these characters have ever been presented. My only criticism is that it's jarring how quickly Cortex and Tropy break out and straight away are in their base. A cutscene showing us how they got there would have been nice.