Does this have a particularly adverse effect on phone battery life, when compared to a well-written app for a centralized social network (aka, not the Facebook Android app; perhaps the G+ app)? I can imagine that a lot of uploading of social network content to your peers would take place.
Also, what is the bandwidth utilization like compared to an app for a centralized network? With a lot of us on tiered data plans now, this is a crucial concern.
I ran the app for most of this morning on my Nexus 4, after adding most of the links in this HN post as favorites. Between 9 and 11 my battery lost 40% of its charge. Ordinary usage tends to yield 14 to 17 hours of battery life from a charge. This kind of impact on battery life will be a deal breaker for most people until resolved.
Spotify's desktop app is P2P, but their mobile app is server-client. Perhaps advanced users could mitigate the battery life issue in the short run by setting up a "proxy" on a server that joins I2P, while presenting the front-end on a mobile device -- like you would with, say, an IRC bouncer.
I own a Nexus 4 and agree with the parent poster. 14 or more hours mostly idle is normal. I get even more if I dim the screen for normal use.
Fortunately, Android JellyBean provides all the data you need to fix your problem. If you are getting worse battery life, you need to check Settings -> Battery and determine which apps are unreasonably eating up your battery life.
Also, what is the bandwidth utilization like compared to an app for a centralized network? With a lot of us on tiered data plans now, this is a crucial concern.