I have been doing alternate day fasting since July and think it's great!
My Mum recommended it to me and at first I thought there's no way I could ever survive on just 500 calories for 2 days per week but honestly I find it very easy now. Of course at the start I struggled and found myself getting very hungry so I cheated a bit but now I drink plenty of water which reduces the hunger and I can easily manage 500 cals a day.
I did a lot of travelling over the summer so was eating out 3 times a day for several weeks. I literally ate whatever I wanted during this time (Ice-cream, fast food etc) but continued with the intermittent fasting and managed to maintain my weight for the duration. I dread to think how much I would have gained if I hadn't been fasting!
I'm now back monitoring my intake on the other days as well as fasting twice a week and so far so good
Everyone is different so I think it's just a case of trialling it for a few weeks to see if it works for you. Decide on when to consume your 500 cals (eg. all in one meal at lunchtime or a couple of smaller meals throughout the day etc.) and if you tend to overcompensate by eating lots on the other days then maybe this diet isn't for you!