In addition to the limited number of categories in the Appstore making it very bothersome to find the music apps you are looking for amongst a thousand "official band" and radio station apps, the biggest thorn in the side seems to be pricing. Not just as in, "that app is too expensive," but also in terms of the volatility of app pricing. I've sometimes benefitted quite nicely from waiting a bit until an app dropped in price (Rectools 08 for example) but also been stung heavily by jumping in straight away.
Anyway, whilst perusing my favourite app-list website I came across this beauty. I mean, when do you jump in and buy this thing?