The WordPress iPhone app slowly improved over the past few months in terms of stability and bug fixes. The current 2.7 release brought a new user interface and was more reliable than before.
The WordPress for iOS team has announced since January, with each incremental iOS WordPress app update, over 75% of crashes have been eliminated. Crashes in January reached an all-time high, but currently has remained stable. Check out the following chart:
WordPress 2.8 is coming soon and will have new exciting features and more stability improvements. I look forward to this upcoming update.
In the meantime, BlogPress has been my favourite go-to app for blogging from my iPhone.