I've been doing this for a few weeks now!
I've been doing the 5:2 since last October, there was quite a bit of a buzz about it following the Horizon programme so myself and a few other decided to try it just mainly using forums, peer support and apps like myfitnesspal etc for ideas. We didn't really do it to lose weight, it was the lifestyle change and the health benefits that appealed to us - most of the others aren't overweight or anything but very health conscious. Most of us lost a couple of pounds maybe over the first 3-4 weeks in total but it's not really something to do for weight loss unless you have a lot to lose. As Rochelle mentioned above, it's no use if you over-indulge the remaining days.
I started SW again a few weeks ago on my non-fast days to actually lose weight.
You can check out my food diary for some ideas if you like, the link is in my signature. I follow quite a few people on twitter and instagram now who post pictures and ideas of what they've had that day - I find that really useful. You need to WEIGH EVERYTHING though and I religiously enter everything on MyFitnessPal. My fast days tend to be a Monday and a Thursday. I also weigh myself weekly on a Friday.
I think that logically, coupled with SW it could potentially give you a boost, but you do really need to look at it as more of a lifestyle change and not a quick diet fix.
Personally, I find it's really changed my eating habits. I don't overindulge on my non-fast days and never really have. It makes me so much more conscious of hunger and the effect it has on me. I also like the challenge of preparing good meals that psychologically make you feel satisfied 2 days a week. I also drink about 3-4 litres of water on the fast days and this has definitely been carried over into my lifestyle on non-fast days.
Hope this helps in some way