I'm always slightly reluctant to order large appliances from Amazon, because of the hassle of returning it if there's a problem. However, they were offering this Karcher package at a cool fifty pounds less than my local Halfords, so I took the plunge.
Delivery was very prompt - the next day at some unearthly hour in the morning a cheery courier turned up with a large and heavy package. Assembling the washer was slightly trickier than an IKEA bookcase, but I managed it. A non-vital part (the loop for storing the pressure hose) was missing but that was not sufficient to justify a return. Inserting the pressure hose in the washer and the other end in the nozzle was tricky - the ends kept falling out until I pushed and twisted them harder. Removing the hose ends was too difficult - I eventually consulted a website that showed me how to do it. The supplied instruction book from Karcher was laughably deficient in these minor but important details.
However, once I had the washer assembled it went like a charm and the pressure and volume of water was really impressive. I had purchased this washer with the included patio cleaner precisely to clean my patio, which had been left to nature for eight years and was therefore hosting a varied and deep selection of flora and fauna. I first tried the patio cleaner sans detergent (thoughtfully supplied) and it made a pretty impressive job on a sample patch. The washer alone could do the job but at a much slower rate. I then inserted the detergent bottle and set the detergent supply valve to "Max". A satisfyingly sudsy mixture came out and applying this with the mixer nozzle and then using the patio cleaner on the sudsy area worked beautifully and did a job which my wife, not an easy person to please except on her wedding day, thought "amazing". Then the detergent dispenser went on strike and then it dispensed a small amount after fiddling. However, I still managed to clean at least 500 square feet of very grubby patio in less than 2 hours and was well pleased.
Overall review - the pressure washer was good but detergent dispensing on mine was pretty hit and miss (mostly miss) and the instruction book definitely needs a re-write with more details about silly but important bits like undoing the hose ends. The patio cleaner itself can be purchased separately but I believe is only compatible with Karcher washers. The patio cleaner itself is absolutely brilliant and does an amazing job on patios - mine even did a reasonable job on wooden decking (I know I shouldn't use a pressure washer but needs must). Washer - 8 out of 10; patio cleaner - full marks!