They work well. I have not ridden them over 50 miles. I am 6' 185lbs, wear 33 waist, am average shape and the size M fits nice and snug. A size L might fit more relaxed. I would not buy super cheap bike shorts, they don't not keep you in place. These do.
Good value for the price for cycling shorts I wanted for moderately long road rides (3 - 6 hours in the saddle). Panel material is robust, and padding provides a firm and stable foundation. Ordered large size based on measurement recommendations on the web site and feel constricted in the crotch - will be exchanging for XL, but everything else (waistline & legs) felt fine. Maybe add a little extra room down in front?
As others have noted, Pearl Izumi shorts run small. I'm a 30, and the WBW size chart says a small should be 29-31.5, but these are borderline tight. (A medium in PI is typically too big for me.) Solid construction, but has an annoying stiff seam jutting inward that sits right on the buttock-will likely soften up with a few more washes, but this is the largest, stiffest, most intruding seam I've ever seen on the inside of cycling shorts.
Bought these as previous year's closeout, so they were super cheap. They fit well and do what they are supposed to do. They don't creep, or move too much. I would be willing to pay full-price for my next pair based on how well these worked out.
Just purchased my second pair to have another pair. Use so far has been completely on a trainer, riding up to 2 hours so far they are very comfortable. No movement, chaffing or soreness so far. Breathability difficult to determine without air flow but I plan to use these on extended outdoor rides as well. Solid.
My wife purchased these shorts for Christmas, I needed a pair for spinning class. I had a old pair of PI and they worked well. The first time I used the new ones I noticed a big difference. Extreme comfort. no chaffing or soreness. Keeps me cool for the most part. These shorts exceeded my expectations, I would even consider using them on 40 mile rides.
This is my first pair of real cycling shorts, and I am totally pleased. I wear them to commute 14 miles round-trip to work, but have also worn them on 2, 25 mile outings with no problems. I would totally buy more of these!