First, given the track record of manufacturers with android security updates, I wouldn't install a bitcoin wallet on my phone.
Then, there is the problem with "buy $5 worth of bitcoin". Last time I checked, this was everything but trivial, at least here in Europe.
And finally, the last purchase I made with bitcoins on steam took more than 12 hours to get validated. I used the standard bitcoin fee of the bitcoin-qt client but it seems to be far from enough nowadays.
Then, there is the problem with "buy $5 worth of bitcoin". Last time I checked, this was everything but trivial, at least here in Europe.
And finally, the last purchase I made with bitcoins on steam took more than 12 hours to get validated. I used the standard bitcoin fee of the bitcoin-qt client but it seems to be far from enough nowadays.