When I heard that we have to wait a few more months until we get a native ipad client for OmniFocus, I began to look into Things, but that just confirmed that OmniFocus was the best app for me, so I'm waiting it out.
But I'm waiting it out in style. If your phone is jailbroken, there is a preference file hack that makes it run as if it were an iPad app. Most apps don't handle this well, but so far. OmniFocus does.
http://tweetphoto.com/21831839
There's an app called FullForce that makes this even easier to implement. This makes the wait for the full version a little more bearable.