As to why it was better or worse, the sequel was accused of being buggier than the original game. Some people also believe that the original game had a darker atmosphere to it. The bugs gripe is true to an extent, but I always found both games to be sufficiently dark and creepy.
For me it wasn't either of those. I think the sequel has a much worse story, and one that actually seriously undermines the original. And the connection to Alice in Wonderland in the sequel is for the most part so tenous as to be almost nonexistant, many levels being just "some weird stuff we just came up with". Hey there, welcome to Weird Chinaland! I don't remember ether game well enough in detail to make an honest comparison in terms of gameplay right now, but I liked the levels in the original much more.
And, of course, the original was, well... original. It was a clever idea and a unique game. Doing it again isn't nearly as interesting.
I'd love to see the first game here and to play it again. The sequel... I doubt I'd pick it up at all.