I did the computerised one *very* recently - part of the requirement to get a JAA one off the back of my existing ICAO one. Much of it has been said already, but I'd offer the following:
I was given a brief which contained a 'plog', however, the computerised plane 'flies' its self along the route - it uses time compression in the quiet bits (which stops as soon as you press the PTT). That means calculated timings are irrelevant. You're expected to use /set QFE/QNH and transponder codes as you go, including correct (standby-change-on) use of the transponder. There was an 'emergency' scenario and a zone transit in mine, as well as the potential for diversion, QDM's, mayday relays and the like.
It also means that the whole thing is quite compressed - Being honest I found I was a little pressured - not flat out, but it was reasonably intense. My examiner advised me to keep it simple, and talk to the minimum number of people - sound advice indeed. I was also advised if it took me more than 10 mins to 'plan', I was overthinking it - I concur there too - writing down too much stuff (I did) is just confusing, I would stick to who, when and initial calls - if you can't regurgitate the responses fairly easily, it's perhaps premature to take the test. A dry run would be worth its weight in gold.