I've been using Toodledo for a few months now in conjunction with Appigo's To Do, and I think it's an excellent website and service. Whenever your app or To Do supports subtasks, I'll likely upgrade my account.
There is, however, one thing I find lacking with the Toodledo service, and that's your iGoogle gadget. I like being able to manage my tasks from my homescreen when I get online, but I find the gadget (which I believe is just your "slim" page) to be somewhat unintuitive.
My main problem with it is it's quite difficult to glance at it and see what I have to do today, tomorrow, etc. All the tasks (in hotlist or all tasks view) are shown with nothing to seperate what's due when. I think it would be a huge improvement to have dividers in there for "today", "tomorrow", and "next seven days" like you do on the website. Furthermore, I don't like that the height is static. Regardless of the number of tasks it shows, the height doesn't change, which makes it take up tons of unnecessary space. I dont think the height can be adjusted dynamically (that is to say, without reloading the gadget), but I think an easy way to overcome this would be to have the height manually adjustable in the settings.
I was wondering if it was likely this would ever be updated. If it were, Toodledo would be just about perfect.