I think it is really great that Google is trying this, I don't want to be too pessimistic either as they seem to always defy the odds, but one of the problems with any type of high altitude platform whether it is LEO, Geosynchronous balloons or otherwise is that they cover a huge area, just by nature, which limits the capacity. Terrestrial cellular technologies get around this issue by being low to the ground so that the RF energy is dissipated and you are able to re-use the frequencies with the next cell over. With such high altitudes that is just not feasible. So I think this approach will always have limited capacity. Also, the fact that it is moving will be a challenge since both LTE and WiFi use OFDMA which is very sensitive to Center frequency offset that can be caused by the Doppler shift as the balloon moves. At 60kft, the uplink is going to be a challenge since most handsets transmit at 200mw max so it will be difficult to achieve high data rates in both directions. There are a number of other technical challenges that are ahead of them as well, but I am very impressed with their perseverance. I hope they are successful.