Mashable has a very good slide show of what people don't like about mobile apps. The slides are worth seeing but if you're time famished, well, here's the short version:
- Too many emails
- Irrelevant push notifications
- When great apps are abandoned
- Frequent "rate this app" requests
- Connecting to Facebook unnecessarily
- Full-screen ads
- Video ads
- Non-wrapping text
- Non-retina apps
- Desperate pleas for followers