Admittedly I've never tried it, but from the description, the pomodoro technique would drive me mad. It often takes me more than 20 minutes (sometimes an hour or two!) to get "in the zone" but once I've got my head in the game I can smash through work for hours. The idea of just getting some flow going and then being interrupted seems awful. The only thing I can think of which it really sounds good for is boring, easy tasks that I have to do but really don't want to.
What makes it so good? Obviously it works for a lot of people.
I use a modified version of the pomodoro technique in combination with David Seah's Emergent Task Planner [0].
The problem you describe is familiar to me - once I am in the zone I can continue there for hours, and taking enforced breaks every 20 minutes would force this streak to end early.
To work around this I just made the breaks optional, and use blocks of 15 minutes (as described in the Emergent Task Planner).
So, my timer goes off every 15 minutes. This breaks my concentration for a couple of seconds so I can reset my timer and tick a box to show I have completed another 15 minute block, and then I jump immediately back in to my task. A couple of seconds is not enough to take me out of the zone, but it lets me keep track of my progress on tasks and see where my time has been spent throughout the day.
Personally speaking, my biggest procrastination problems arise when I lack clarity about exactly what I should be working on at this precise moment, or when I finish a task and need to think of what to do next.
My bastardised pomodoro technique solves this problem for me by always making it clear what I should be doing right now. If my mind wanders for a moment, or I get distracted by an urgent task, this list allows me to immediately refocus without any mental effort. When a task is complete I might take 5 minutes as a break, and then jump on to the next task.
If my procrastination problems sound familiar I highly recommend the ETP approach. Print out five of them, grab a timer set to 15 minutes, and give it a try for a week. Make it part of your morning routine - plan out what you want to achieve for the day, write it down, and start the timer!
It might not be appropriate for all kinds of work, but there is also a flow aspect to the rhythm of work and rest. Try it for a couple of days and see what happens. The break times may not be as disruptive as you imagine.
It's also (as i was taught) a way to break up the mental processes, giving your brain time to analyze your problems without being so intently focused on them. "Focused" mode for 25m, "Diffuse" mode for 5m
I recently learned of this via a MOOC, and oh man has it been helping me. 25m chunks of work are much easier to push myself through, and the 5m breaks really give me a sense of freedom.
The length of the day also doesn't seem to weigh on me - i just focus on being completely on task for 25m chunks at a time, and the day flies by. No more `compile; open reddit.com`
+1 whenever I really need to get stuff done at work (and particularly helpful when working from home), I split my time into pomodoros. 25 minutes is a short enough time I can fully concentrate, but long enough to actually get a great deal of "knowledge worker" work done.
What makes it so good? Obviously it works for a lot of people.