We were going to use it. It was about £15 each I think and was supposed to include a buffet and a drink. However there was no buffet that day and they said they'd get us something from one of the cafes. Anyway we decided not to bother.
One thing I will say, make sure you have the correct money - 15€. I didn't and got short changed by about £8 - not a lot of money in itself, but ......................
I also didn't think that what they had on offer the time I was there was worth 15€, but that was just my opinion.
It depends; if you intend to eat at the airport you will find that the KFC/Macdonalds fare is hugely expensive. If you pay for the CIP lounge (so called) you can eat as much buffet as you wish (which was on when we were there in May) and drink as much soft drink as you want. The food was plentiful and topped up regularly.
As we were travelling with our 14 month old (who had found out that day that she could walk - great excitement) and the flight was delayed for 3 hours, we found it made a lot of sense.
I think there is WiFi also but I may be wrong; there is certainly free internet access from some pcs there if you want it