The official Boris bike app is lame, but fortunately no user of Boris bikes ever has to use it, as they have a solid API. You can get a fantastic experience with apps like CityMapper, which incorporate Boris bikes into the overall public transport landscape. They show you live maps with availability. (Hopefully they'll integrate the newer bike platforms too soon.)
What has stopped me from using the Boris bikes is how unreliable the payment system is. It seems like there's a 25% chance that any given bike station will reject my card for an unknown reason.