Thirsties Diaper Covers are a good fitting PUL (polyurathane laminate) cover suitable for a variety of baby builds. Coming in a variety of cute colors, we have found that while they're great over fitted diapers, they really shine over prefolds. This is where their near bullet-proof construction has saved our laps and carpets both through the breast-fed leaky poo stage, and the introduction of solids. The leg gussets are a fantastic feature, catching everything our baby has thrown their way. And the elastic has held up on both the waistband and leg holes, preventing blowouts. Additionally, none of the covers have stained.
We have, for the most part, washed our Thirsties covers in the same loads as our prefolds. This means that several times a week they're going through a cold rinse-hot wash-cold rinse cycle. Then they're tumble dried. As we have six covers on rotation, they go through a lot of use and cleaning. So, keep that in mind as I describe what has happened with them:
First, the covers can all still be used and none are leaking or wicking. However, due to our rough treatment of them, we have found that the aplix band on the front of several covers has begun to separate from the cover surface at the stitching. Several of the laundry tabs are also separating. In one case, we have had the PUL material begin to stretch with the fibers becoming distressed. So I would recommend that if you're going to treat these like I have, buy a few more of them. (Okay, I'd honestly recommend more regardless, if you'll be in cloth full time. I get buy with six by washing sometimes twice a day.)
In summary: these are good, workhorse covers that look cute and contain everything. They take a LOT of abuse, but if you abuse them day in and day out, expect them to lose some of their good looks. I'd recommend these to anyone looking to cloth diaper over prefolds or fitteds.