WAIT - Ask another existing customer
I've been using Things - both the iPhone and Mac software - since late january and I'd like to add some balance to the review, and some balance to donnacha's comments.
First off, the review. With any piece of software, you should read a little before jumping in. Cultured Code are very clear that the Inbox is where you create stuff you don't want to, or can't yet, classify. It won't appear in any other view. If you don't like working this way simply do what I do and create new tasks in the 'Today' view instead. I don't use the Inbox at all. It's that simple. RTFM, and you won't get confused about things in Inbox appearing nowhere else. Perhaps Inbox is badly named but the way it works IS quite clearly explained.
As for working in an organised fashion: About 70% of all my tasks appear in 'today' and never leave until they are completed. Every so often I have a group of tasks I decided to put into a project. Using Today to create your tasks you are never forced to organise anything, unless you really want to. If I was forced to organise stuff I wouldn't be using the software. I have attention deficit so being organised has to be optional!
I don't think this reviewer has really used Things for very long, or tried to get beyond their mental block with the Inbox. Things for the Mac is also a very good product and the two synchronise seamlessly for me.
Onto customer support. When Things was released, yes, with a few flaws, Apple also put out a new iPhone 2.x release and some people had problems with synchronisation as a result. The feedback I saw on some Mac forums made it clear that Things had become quite popular very quickly and I'm sure this would have affected the level of support that Cultured Code, quite a small company, was able to provide. I was one of those people and once I'd reported my problem on the forums I was asked to try a few things to help troubleshoot. Within 24 hours a new version of the software fixed my problems.
Others may have had less smooth experiences but how much one-to-one support do you expect for £5.99? This is the elephant in the room with iPhone apps IMHO - you can't expect much support for any piece of software that costs less that £50. I have visited the forums from time to time and whilst I can't vouch for the presence or otherwise of Cultured Code staff, I can't say I ever noticed that the forum links disappeared.
donnacha is clearly not a happy bunny but I have been completely happy with the software, both Mac and iPhone, and the support when I have needed it. There are one or two small annoyances that I'd like to see addressed but these don't stop me using it effectively.
Things is NOT a simple task manager or notes application, it goes beyond that to the point that I use it to track and control all my one-man projects and will continue to do so.