I've been using Things for about a month, and I love it. I find that Things stays out of the way and helps me interact directly with my actions, projects, and contexts without too much interference. I was able to start using Things right away, there's not much of a learning curve. Things provides exactly what I need in a GTD application.
(Sorry for the bump, but this is a difficult topic to search for, and I was looking for some info abt it.)
I've been using Things for a few months now, and it does what I need it to do. I like how easily it seems to integrate into the ToDos in Mail, and I also like how easily I can link a particular e mail to a particular task. The iPhone app is great, but I wish it did cloud syncing since I actually only have an iPod touch that I don't always remember to sync...
The sections for Areas and Projects are also nice for keeping a clean inbox and really being able to visualize the work that needs to be done. I'm not sure I'm fully utilizing the power of it right now, but I don't find it to be lacking anything, either.
I don't have it completely set up across the board with Mail and iCal, but it fits pretty well into the workflow I've established. I need to streamline a few more things (find out if some areas need to be consolidated or if they work on their own), but overall Things seems to work pretty well for me.
My wife uses things on both her mac and the app for iPod touch. She loves it. It sycs through wifi automatically anytime the two are connected in the same location.
ONe thing my wife likes about the organization part is that you can have several projects each with multiple steps. She can select the next button and view the next item to be done on each project.
TheHitList looks interesting but it hasn't really been worked on for almost a year now. And it's been well over a year since they started talking about having an iPhone app. Not sure I'd throw money at someone who's isn't really doing much with their product.
I used to use iGTD, but that has an odd syncing problem now and the developer left to work on Things.
I started using Things on a trial basis about a week ago. Overall I like it, but I'll probably trial OmniFocus too. It appears to be a little more GTD aware, which I like as an organizing principle.
Still a little floored that these Apps cost so much for what they do. Basically they are a GUI for the post-it and pen scribbles I can't keep track of!
$50 is quite a bit, but at the same time, it just works. What else are you willing to pay for that "just works!" It is a great program- my wife still loves it and it syncs perfectly.