Basically it is an alternative to washing up liquid that is a lot faster to work with as you have a lot less detailing with a scrim to do.
There's also less mopping up of the sill as there's less water spashed about.
I hated it at first - now I wouldn't use anything else.
All the usual window cleaning suppliers stock it - try scrim city they sell it cheap. It sounds like a lot of money (£20.88 + VAT), but you only use 5 - 10ml per bucket.
I hope this info is a help to you.