I graduated 2 months ago and have been concentrating on getting up to the mythical 5k, without worrying about speed. Last week I got there, taking 47 minutes.
Today I wanted a run, but was a bit short of time, I definately didn't want to spend an hour (by time you add warmup and cooldown) so I thought I'd give speed a go. It definately gave me a good workout ! I also confirmed (in case there was any doubt) that i have no sense of rhythm - running on the beat was very hard. I think I might include it as my workout once a week for a wee while and see how I get on. I just ran in a loop round my local park.
Anyway, worth a go IMO.