Crash 2 is the best in the series with only a few flaws such as
-No checkpoints in the death boat runs.
Challenging game design is NOT a flaw. Forcing players to get good at your game instead of allowing them to save their progress after every single obstacle is NOT a flaw.
It should be noted that a few of the longer secret areas do have checkpoints like the red gem path in Snow Biz or the secret area in Unbearable. They don't appear in the shorter ones, however, because the designers recognized that using checkpoints as a crutch to make difficult sections easier is bad game design.