Got 100% in just a bit over 10 hours. The game is a joy to control and the music/art directional is fantastic. That being said:
-The game wasn't as difficult as I thought it would be, so in a sequel, I'd like to see a higher difficulty setting. Most deaths happened during chase sequences.
-The collectibles were too easy to find and didn't require much thought to acquire. As a result, the abilities to see these power-ups and secret areas on the map were rendered useless for the most part. I chose those skills as my final upgrades because of this reason.
-The chase sequences were good, but they're hampered by all the environmental effects which obscure the parts of the screen where you view your character. This makes it difficult to see what you're doing at times. Also, your skill/speed in these sections is meaningless because the game "cheats" to catch up to you if you're progressing too quickly, but I suppose that's what helps add to the tension.
-It can get tedious to travel across the map towards the end of the game if you want to finish up collecting things. A few warp points would have been great.
-I got tired of seeing the same types of enemies and taking them down in the same exact ways towards the latter half of the game. More enemy variety would help in a future title, or at least, souped up versions of the regular enemies with different attacks/attack patterns.
-More underwater sections. I enjoyed swimming in this game and felt like there wasn't enough of it.
-Allow players to head back into the dungeons if you're going to place collectibles within them.
Overall, it was an enjoyable experience with tons of charm and definite room for improvement. I'd give it a solid 8/10.