The game has 3D effects, but it is mainly played in 2D. The skills are the same as in the original game, so the gameplay is similar. Since the level is a cylinder, it is possible in some levels to go all the way around in a circle. Imagine a level in the original game in which the right side of the level wraps around to the left side.
The game also has several other features, including teleporters, anti-gravity pads, and switches and gates that can trigger retractable walls or fill/drain pools of water. Also, some levels have a separate "species" of lemmings that can walk on water or acid. There are also bad guys on a few levels, which act just like lemmings, but they kill any lemmings they run into.
I haven't seen the game available commercially recently, but based on a recent thread here, I think you still may be able to buy it cheap if you're lucky enough to find it. I don't know of any websites that offer it, legally or not, so you may be out of luck there. You can always try Ebay, though.