I use Things on my Mac, on the iPad and on iPod Touch
I have to say, my iPad version of Things get the least workout of the three. Here's a rough outline of how I work with Things.
On Sunday, during my Weekly Review I work exclusively with the Mac version of Things going Area by Area moving things out of NEXT into SOMEDAY and out of SOMEDAY into NEXT. I also adjust SCHEDULED (=calendared) and REPEATING tasks in each Area of Responsibility (I have about 11 areas).
After I am done with my Weekly Review, I sync all changes to iPod Touch and iPad.
During the week, I work mostly with the iPod Touch version of Things.
Every morning, I sync all three versions just after I wake up. All I have to do is turn all three devices on, and it takes less than 2 minutes to sync al three (Older version would go for up to 5-6 minutes).
I then star anything in NEXT for TODAY if it's not TODAY'ed yet or vice versa knowing the forecast of my workload for that particular day (I intuitively sense how much I can get done)
That's it! For the rest of the day I work out of the TODAY list (which is essentially Priority 1 subset of the NEXT list). TODAY list is simplu items in my NEXT list that I have deliberately chosen to work on. Each day I have roughly 15 tasks in TODAY and each week I have about 40 tasks in the NEXT list altogether across all 11 areas. I only touch the SOMEDAY list once a week during the Weekly Review.
Those who are familiar with THINGS way of working GTD would know exactly what I am talking about.
The cloud syncing for Things is still in the works and is eagerly awaited by many. I just remember to sync one a day.