Just got back from Stormy Ascent.
I can't say how it compares to the original and what makes this version "finished" in comparison to the original, which was an unfinished level. But it's pretty challenging and one of the hardest levels in the game. I still find the N. Sane version of High Road harder so if you can do that, you can do Stormy Ascent.
Overall I didn't find the level overwhelmingly hard, it's more of a "here's a stretch of challenging and fast paced and flowing platforming followed by a more tricky part that requires thought and trial and error" kind of level. The box gem isn't really difficult to get either, all of the boxes are practically given to you for free after certain sections so you really can't miss any. There is an N. Brio stage but it's more of a box manipulation puzzle than a platforming challenge. You're guaranteed to fail that part at least once though since it has a few parts where you'll only know what to do after failing.
There were a few slightly buggy parts though, mainly some of the slippery, brown stairs. Some of them have a bit of an extra metal plating sticking out of the end of them, so when you're trying to run and jump right at the edge, Crash will start spazzing out on top of it which will eat your jump and you'll fall.
Overall it's one of the more fun levels in the game and fits right in.
In case you're wondering where the level is located, it branches off The Great Hall and has a purple colour dot on the world map. The game shows you anyway. They also added a second purple dot that teleports you between N. Sanity Beach's space and the area where Stormy Ascent is, which is nifty for anyone who is backtracking to earlier levels, it means you don't have to fully run to each end of the map anymore. Completing the level with the gem will make your clear percentage 102%, assuming it was at 100% beforehand.
Oddly enough, I did not have to download an update or download the DLC separately, it said I already had it purchased. Maybe digital copies come with it for free?
As far as I can tell, nothing else has been done to the game under the radar (I didn't have to download an update, so...).