In Dungeons and Dragons Third Edition, these boots have changed quite a bit. I almost find them a necessity for any halfling character (in my case, a rogue named Calloway). Their effects seem a lot less exciting than the old first/second edition version, but they are tremendous.
First, they allow you to double your movement rate. (Halflings, which move at 20' per round can now move at 40' per round, which is faster than the unenhanced human of 30'... Very nice.) Then they give a +10 competence bonus to your jump skill. Finally, they remove the restriction of jumping distance that was related to your height. I had a poor little halfling that discovered that rule when he found that his natural 20 still wouldn't save him, since he was 2" too short (as a character) to be able to make it from building A to building B. Ouch.
The reason that the boots are quite so powerful is that movement in the new system is extremely important. There's some definite strategy in the new edition of D&D, and you want to place yourself on the map in the best fighting location you can. (And if you need to run, being able to outpace your opponent is nice.) The original price was 2,500 gold pieces, but when they discovered the many many uses, they increased the price to 6,000 gp. (They did similar things with Wings of Flying and all other wonderous magical items which increase your speed.)