I had recently switched from OmniFocus to Things for a trial comparison of the 2 main GTD apps for Mac. I have a purchased copy of OmniFocus, but was finding it a little frustrating trying to track multiple home & work related projects, and using it as a system you can trust to store ideas and someday/maybe tasks using only a single context to identify each task.
After using Things for a few weeks now it feels like a breath of fresh air. It's tagging system is very simple, but incredibly powerful. I love being able to process my tasks and quickly move a bunch to the Today focus, and then using the tag filter further refine my next actions down to either general work/home related tasks, or a specific context.
It also has a strong someday/maybe and scheduled concept. Tasks in the Someday focus don't vanish completely, but appear in a collapsed section beneath your active tasks. Scheduled tasks automatically move into the Today focus on their scheduled date.
I'm also loving the Projects and Areas features. Projects can have tags which automatically apply to any tasks added to them, but can also be assigned to an area such as Work or Home. For me it's more in keeping with the GTD definition of a project being any action that requires more than one step to complete. OmniFocus on the other hand left a lingering feeling of hierarchical structure makes tasks less accessible.
Anyway, there's a perspectives screencasts video for OmniFocus out that made me think how much it points out the difficulty in accessing tasks in Omnifocus.