You can do up to $500 in any rolling 24 hour period and up to $1500 in any rolling one week period. There is a $1.50 fee by PPATM (in addition to any ATM fees) and I think there is also a $1.50 fee for point of sale purchases.
For the first $1500, they are better than NETeller. But over that NETeller is superior because they have $1000 per day ATM limits, I don't think any weekly limits and you can make direct EFT deposits for higher amounts whereas Pre-Paid only does checks and bank wires. But the checks are mailed from Ohio so they only take a couple days.