I went on one of the ones in Edinburgh last year. Have to say that I found it to be very useful, from the point of view that I had read numerous "manuals" but lacked the confidence to actually tinker with my bike.
The course begins with the basics, such as taking the wheels off the bike and putting them back on, progresses on to removing the tyre to repair a puncture (they give you an inner tube to practice on - rather than ask you to ruin your own.), indexing the gears (including hi/lo adjusting screws), installing new brake-blocks, removing the chain (using a chain-splitter). Also went through the important areas of the bike to make sure are kept well lubed.
In the afternoon session we looked at some of the more tricky things like removing/replacing the bottom bracket, removing the gears cassette and finally looked at truing the wheels.
The lunch that was included consisted of a filled roll (you place your order at the start of the day), drink and a cake.
Everything was carried out at a pace dictated by the group members - and as we had bikes ranging from racers to audax to disc-brake mountain bikes, we were able to get an appreciation of the intricacies of each.
Would say it was definitely worth the money.