Pros: Washes well, cute prints, size 1 fits well, gussets
Cons: size 2 doesn't fit well, velcro wears out really quick
We used the duo size one for my baby from age 2 months to 7 months and then size two from 7 months until 11 months.
I really loved the size one and told everyone Thirsties were my favorite diaper. They fit well, the snap down rise worked really well and the velcro was strong after my baby outgrew them (5 months use). I sold them on Craigslist and they retained their value pretty well.
We ordered size two and I just wasn't as impressed. The size two seemed HUGE compared to the size one. The snap down rise just wasn't as effective with the size two, either. It made some weird creases and folds and caused the diapers to leak. We ended up just using them full size and they were just way big. We only used them for four months and then we opted to try something else. My son had figured out the velcro and rather than try Thristies in snaps, we tried a different diaper cover and I like those better.
The velcro on the size twos did not hold up well. We used the covers as back up in the diaperbag and if we ever ran out, so they continued to get used a few times a month and by now (about 9 months after we bought them) I'm not sure I could re-sell them. I know they wouldn't last for a second baby.
I washed them with all my other diapers in gentle detergent (never bleach) and I always hung them to dry.
I will say that Thirsties has excellent customer service and when one of my diapers had a broken snap they sent a replacement right away complete with pre-paid envelope to send them back the damaged cover. They then fix those covers and donate them to families in need. Great program.
Overall, I was happy with the size one, not so much the size two. If I had it to do all over again I'd be happy to use Thirsties for size 1, though I'd chose snaps. I don't think I'd use size two again, though.