Top idea but...
...local rates are slightly disappointing. 15p to every network in the UK is more-or-less fine, but making a call to say Poland costs 8p to landlines and 20p (!!!) to mobiles. It's even more pricey than similar payg offerings form "big" networks like Vodafone or T-Mobile (both 5p/15p), not to mention MVNOs like Lebara (2p/9p).
Having used Truphone Anywhere happily on Symbian-based handset before, this offer is quite disappointing to me, unfortunately.