It's certainly not a scam. I've used it just fine (including...

It's certainly not a scam. I've used it just fine (including minutes and world credit recharges). Also for what it's worth I have been keeping track of the number of ratings in the google play store, and wp at the moment is clocking up about 100 new star ratings per day. Most of these are positive and give it 5 stars and the overall rating in the Google play store is 4.2 based on a total of around 19,000 ratings. Skype has a rating of 4.1 and viber is 4.3. While these two apps have more votes in total they have a similarly large number of people giving them one star ratings to wp.

https://play.google.com/store/apps/details?id=com.norwoodsystems.worldphone&hl=en

Reading some of the one star ratings for wp (and other similar apps) my opinion is that some ppl aren't very good at using apps and if it doesn't work straight or they misinterpreted what an app does they just give it one star and move on. The credit issues with wp are concerning however the numbers that this affects still seems low as most ppl are still giving it high ratings.