I think in the beginning, you won't be smooth like you would with shaving. It takes a couple of hair growth cycles before you can achieve a smoother finish. I have noticed that sometimes when you quickly run the epilator over your skin, it causes the hair to break.
All of the newer epilators basically use the same tweezing mechanism as opposed to the original Epilady which used a coil. The more expensive ones include additional features. Probably the most important feature is how fast it can remove hair. If you buy a cheaper one it will take more passes to clear the hair.