I only played the original PS1 game once, in fact the Wii remake was my first game. I really like the graphics, but compared to the original it's really lacking in many parts. Klonoa has no real personality here, so I can't really feel for the game as much as I found myself with Klonoa 2. The cinematics of the original are far superior obviously, far more colorful and enchanting, while the Wii one obviously lacked the detail and the charm in that. I was also disappointed at how the cutscenes were animated. It's like they rushed it, and didn't have time to fully animate the characters in the cutscenes, instead just switching between idle animation loops and actions, making the characters feel stiff and lifeless. The way the characters behaved totally reminded me of scripting npcs in Half-Life mods, and that's ancient. I know the same technique was used in Klonoa 2, but there it was done very well.
Also difficulty was reduced, and Klonoa 2 wasn't very hard to begin with, so there's not as much of a challenge. And for the voice acting, I liked most of the English voices, but Eric Stitt... just really made Klonoa feel weird. He sounds like 17, when he's supposed to be what, eight? Now I would switch over to the Phantomilian, but apart from Klonoa's voice actor, everyone else just sounds... awkward, like they didn't put any effort into making it sound like actual gibberish. Like it was just done in a hurry.
So yes, I prefer the original. Now of course I'm not saying the Wii remake is bad, it's a good game, but so far it's the game that has the most flaws, and that's gonna stick out in this franchise, where the main games are nothing but masterpieces thus far.