It's a bit too bloated for its own good at points, but Crash 4 is the gold standard for reviving a dormant IP, taking the series to the modern age so gracefully that it's almost like it never left.
As for the grueling completion requirements, I honestly don't mind them, it's fun to slowly chip away at it, and it's incredibly rewarding getting all of the gems for each stage. That said, N. Verted levels did not need to exist, and are easily the worst part of the game, just being copy-pasted versions of the same levels, but mirrored and with a usually obnoxious filter effect placed over them. Everything else, though? A ton of fun, and easily the sharpest entry in the series.