I always loved how things looks and its simple, elegant user interface. The iPad version is simply beautiful: it works exactly the way a task management app on an iPad should work.
Unfortunately, Things’ syncing has never worked smoothly. Syncing it between two different computers can only be done with something like DropBox, and you can’t run it on both machines at the same time when using the same data file. Things can also sync with iCal, but that always causes duplicate & missing items and doesn’t work at all between two different machines sharing a data file. Things usually syncs nicely between a single Mac, iPhone, and iPad, but today it suddenly stopped recognizing my iPhone, even after I removed it and paired it again.
OmniFocus is a lot more powerful and flexible, but as a result it doesn’t feel as clean & elegant as Things. OmniFocus has a major advantage over Things in syncing. While Things only syncs mobile devices over the local network, OmniFocus supports several different syncing methods, including MobileMe. OmniFocus can only sync manually with iCal, but it doesn’t screw up the way Things does. Most importantly, when syncing via MobileMe, you can run it on two computers at the same time without screwing anything up, and you can sync your iPhone even when you’re away from the computer.
Due to all of the syncing problems I’ve been having with Things, I’ve switched back to OmniFocus. Unfortunately they still don’t have an iPad version, so the iPhone version (like most iPhone apps) is just plain ugly when run on an iPad. I miss Things’s beauty & elegance, but not losing data is more critical.