If you mean, for example, how much coal you get from lignite, I don't think any numbers like those have changed. As for other features, there's a few condensed lists of new features and bug fixes in the release_notes text file included with the game. 33c... There's been quite a few changes since then.
Religions, wars (worldgen only, but if worldgen ends with a war going on it can affect who you get sieged by), and a cool advanced parameters thing when making a world so you can make a massive desert world devoid of elven life if you want, but it's difficult to figure out how to use. Also, there's a world painter, but I wouldn't reccomend it.
Also, due to a new ethic system so complex even Toady has a hard time figuring it out, goblins have gone from the scourge of the lands to a quiet, peaceful race (albeit one with a lot of slaves), and Elves have gone from mildly annoying hypocrite hippies to cannibal zergling hypocrite hippies.
It's a tad slower now with default settings, but there's a new speed-affecting performance option, PARTIAL_PRINT. It basically makes the game not refresh the tiles that don't need to be refreshed until they need to be refreshed. It makes it faster, but the downside is it can cause nasty flickering on some computers. Fiddle around with the number in that option and the GFPS cap until you get a result you like.
Yeah, go ahead and download it, there's lots of new crap.