Adidas AdiZero PR Review: The New Weight Champ
At 3.9 oz I was wondering weather I was really going to get a shoe, or just some cardboard and fabric. It took me about 2 seconds to confirm the PRs were definitely the lightest, most comfortable racing flat I'd ever strapped to my feet (and this one really is a racing flat - I won't be training in them since I don't think they'd last 100 miles). Then it took 1 5k race on the track to set a PR in the PRs (sorry) that confirmed they perform up to snuff too.
The Pros: They're crazy light, ultra flexible, and ultra comfortable. Longest I've raced in them is 5k but I bet they could go longer if you're the type who's used to flats. It has to be a nicely groomed course though due to the con below....
The Cons: The sole is light but not made to be durable (but who cares - if you're buying shoes that weigh under 4oz you know what you're getting). The bigger downside is that the bottom of the shoes has a number of slits in the bottom that seem designed to pick up every pebble you can find on the road. I'm guessing it's what helps make the shoe so light, and it's no issue on the track or a good road, but on anything else be prepared to pick up some stragglers or do that weird shoe scuffle on the ground to knock the hitch hikers loose.