I ride clipless in Look road pedals. I had SPD mountain pedals for a while, but I didn't like them. Here's my two cents.
Road clipless is so much nicer to ride in, but the shoes suck to walk in. Mountain clipless (SPD, eggbeaters, etc.) are still nice, but if you plan on doing any major backpedaling or skidding, expect to have them randomly eject your foot occasionally. If you don't do any of that, go for it, cause the shoes are easier to walk in.