1. Fill it with water, wait for it to heat up. (4-5mins)
2. Use it for 5mins.
3. Wait for it to cool down enough to be able to refill it. (15-20mins)
4. Go back to step 1.
While you're bored at stage 3, use some good old fashioned elbow grease and remove that nasty stain in seconds instead.
I don't quite agree with that.
I bought one because... well because I wanted to try it, to be honest.
I have one of these:
http://www.lakeland.co.uk/22628/Shark-Steam-Pocket-Portable-Steamer
Personally, I think it's good/great. Not amazing, but not bad. It doesn't do the floors very well, as it's a handheld but I didn't really buy it for that. I just use a mop for that anyway.
What it's good at:
Sinks/Bathrooms
Cooker Hob
Worktops
Extractor Hood
Steaming Clothes
What it's not amazing at:
Cleaning mucky grout in showers - not sure if it's meant to be good at this, but it's not.
What I've not tried it at:
Steam dusting(?)
I find that it takes about 2 mins to get up to temperature, after which you can just keep refilling the reservoir (which lasts about 5 mins of constant steaming) and it does produce a good amount of nice, hot steam.
It gets things clean with a little wipe/scrub with a cloth / brush. It did a great job of my kitchen sink/taps - just required a wipe over with a kitchen cloth for a nice sparkling finish.
It did a great job of my greasy cooker hob, and again only required a wipe over with a cloth to mop up the water it left behind. I did use the brush attachment on this, though... Has plastic bristles, which do kind of bend after not that long using it, but still seems to work ok and I've not used the spare brush yet.
Kitchens and bathrooms it's good at, and came with a squeegee attachment thing for shower enclosures - did a goodish job of that. Probably could have done better with a scouring pad and some Jif, but hey.
What it's brilliant at is cleaning stainless steel cooker hoods. Mine was kinda disgusting with grease, but a once over with this thing and its big cleaning pad - not a mark on it, and it was CLEAN.
The best thing is you don't have to wait for it to cool down between fills. If I had to then I'd say don't bother.