It would be helpful if the folks that are encountering this could provide as much information as possible in their reports. It's possible that folks in this thread are actually having different problems.
The first thing OmniFocus does when starting up is show a static screenshot of a grey screen with an empty Loading bar. Freezing at this point indicates that one set of possible problems.
Next, assuming you have Auto-Sync enabled in preferences, we query the network and start pulling your sync data down. The first 75% of the loading bar reflects this process. Freezes during this part of the process indicate a second set of possible problems.
During the last 25% of the Loading bar, we're doing work on the phone, reconciling the transactions pulled down from the server with the ones that already exist on the phone. Freezes or crashes here indicate a third set of possible problems.
Stale client files could cause problems in the second or third stage, depending on the user. If you're syncing two devices, that would be the first thing I'd check.
Now, OmniFocus for Mac is currently benefiting from a change that the iPhone version does not have. It's designed to help folks that sync between three or more machines by making it easier for OmniFocus to remove transaction files from their server database.
That change could also help folks that are hitting problems in the second or third stages I mentioned above. It is important to note that the change would not help folks that are freezing in the first stage, and it's not going to help folks that are not syncing, or that are syncing fewer than 3 devices.
We'll release a new build of the iPhone app as soon as we can. In the meantime, the steps mentioned in this post may help:
Keeping Sync Speedy
Now, this is the part where I disclose that I'm going to be out of the country for the next three weeks, starting tomorrow. I'm planning to check the forums while I'm away - it's a working vacation - but folks that want
guaranteed help with problems like this should send email to the
support ninjas; we've hired several in the last couple of weeks, so that avenue of support is much less dire than it was a month ago.