I've been doing the 5:2 now for 4 months, and it suits me. I don't find the fast days difficult at all, in fact I always feel quite virtuous at the end of the day (must be the Puritan in me!). And of course I always know that the next day I can have whatever I want. Such a treat after any other diet I've tried, as they've all spoilt my fun at some time - having a meal out with family or friends and silently calorie counting your way through it, and making dismal choices (second glass of wine or pudding?) isn't much fun.
The 5:2 has made me appreciate my food much more too, and though it sounds really pompous, it has also made me thankful for the fact that I can eat more or less what I want when I want, not a luxury afforded to most people in this world.
I'm not doing this one primarily to lose weight - though I have lost over half a stone while eating more than usual for 5 days each week. I was convinced by the health argument, and wanted to try something natural that promised to reduce my cholesterol levels, blood pressure and risk of developing Alzheimer's.
And I honestly think it is good for you. The last three times I've had my BP measured over the past 3 years, it's been a constant at around 134/85, which I haven't been happy with. I had my second Biobank check up at the weekend and it was measured at 118/74. For reasons I won't bore you with, I'm doing much less exercise now than I was at the time of the earlier checks, and I've now allowed more treats like cakes/chocolate into 5 days of my week. My job is particularly stressful at the moment too. I feel my BP should be higher now, and can't think of anything but the 5:2 that could have prompted the dramatic drop (apart from a bungling health professional doing the check, but I've discounted that - my man looked very competent!).
I found The 5:2 Diet Book: Feast for 5 Days a Week and Fast for 2 to Lose Weight, Boost Your Brain and Transform Your Health by Kate Harrison helpful - another Kindle download that's as cheap as the chips I now dare eat.