The futsal forum is a lonely place so you might not get much joy. I am reffing outside the UK so i can't comment on the course or "worth". Personally, round my way, futsal is tough because it is popular and therefore mixed ability and mixed understanding (including my colleagues, ahem, and sometimes mice elf). There is a lot to learn (counting, dangerous vs non-dangerous sliding tackles, awareness of GK slides, use of the hands), there is quite a bit to the signalling (counting, foul after advantage) and a few extra steps to concentration (GK 2nd touch, movement with 2 refs, checking cumulative fouls, scorers and assists with timekeepers etc.)
I really enjoy it, mostly because you have to be sharp and it can be a real cauldron - if you can handle the emotional intensity of a heated futsal game it is very good practice for the 11-a-side. I also run enough to work up a sweat so I don't find it boring at all.