First off, let me say how crazy difficult it is to find teeth whitening products over here! However I finally found some, on the bottom shelf in a corner in a pharmacy near where I work, I saw this White Kiss mouthguard whitening kit for €20 or something ridiculously cheap like that and thought I'd try them out. Apparently they're meant to be non abrasive and restorative of the enamel. I don't know if that's true, but I like to think positively!
You're provided with mouthguards, which you have to mold to the shape of your teeth (the process takes all of five minutes). Then you brush your teeth with the special toothpaste supplied, and finally apply the whitening gel to the mouthguard, put the mouthguards on and leave in for an hour.
Just took the mouthguards off and I'm quite happy with the results! My teeth are certainly not blindingly white, but are definitely whiter. There's loads of gel left in the tube and another tube of gel not used yet, so I imagine I'll need a couple more tries before they get as white as I would like my teeth to be.
I have never tried Crest Whitestrips, but as I've got nothing else to compare this to, I'm pretty happy with the result, considering it's only one hour! I also haven't experienced any pain or anything so far. I'll post another photo soon as a little update. I think I'd buy this product again, but if you're looking for instant results I recommend going with another product.