Ok, so I've just cleaned the bathroom sink plughole and around the taps. It's been video-ed and DH is uploading it now :) I'll do a load more cleaning over the weekend.
We already have a Polti Vaporetto Evolution steamer so I'm already familiar with using one. I've compared against the Polti below were appropriate.
Did you find setting up the Steam Cleaner easy, were the instructions helpful?
Intuitive to set up and I naturally released the steam from the steamer at the to depressurise the tank. There didn't seem to be obvious mention of this in the book. I also emptied the tank at the back but I wasn't sure if I needed to do this every time or only when descaling. Other than that, I guessed how to continually refill the tank and it was easy.
What were your impressions from the first few uses?
It's small and light. I like that the tank can be refilled but it is small, so I guess that's a must. I don't think I'd get much cleaning out of one tank. The locking mechanism for the attachments seems okay but the joints wiggle a little, I wonder if they might leak steam over time.
Compared to our Polti, the Karcher seems a little plastic-y. The Polti is a similar price yet has more sturdy feeling, however it is heavier. For example the bristle nozzle only clicks into place on the Karcher but it screws into place (with metal threads) on the Polti. However, the Polti has no water indicator and takes 15mins or so to refill. The big bonus with the Karcher is the continuous cleaning ability.
Where have you used the Steam Cleaner?
As yet only the bathroom sink plughole and around the taps. Over the weekend I will give a floors a go and the detergent drawer in the washing machine. I might try the patio doors but the Karcher didn't come with a squeegee.
What cleaning chore have you been most pleased with the results from using a Steam Cleaner?
Will update on the question after the weekend when I've had more chance to play with it.
Did you you use this for more functions than you originally planned?
No. Our Polti steamer has a window cleaning attachment with squeegee and also an iron. The Karcher being tested didn't come with either of these so I therefore won't use it for anything more than I intended.
Overall, I'm impressed. It's small, light and the continuous cleaning water tanks are a clever addition. I like that the attachments all clip onto the machine too, but there's no where to put the cloths if you've put the power cable in the storage area on top, this would be something to improve on. I would have liked a glossy flyer of all the attachments you can buy. I've used it, I'm excited at the possibilities, give me something to look at all the things I can buy to go with it 
CONS: only one cloth of each size included which is pretty poor. I use a clean side of the cloth per floor area cleaned, so with only one cloth I would only want to clean two floors. You can obviously use any other cloth you have lying around the house, but surely including two of each size isn't a big additional cost, especially with a machine costing the best part of £200.