Gaijind, it's at Gate 1 of Creek Park. From the entrance, walk straight towards the red/ yellow/ blue building. You pay Dhs 5/ adult, Dhs 3/child to enter the park, then Dhs 15/ adult and Dhs 10/ child to enter the childrens city bldg. Open from 9 am everyday except Friday, when they open at 4.30pm.
Mine is 4 and still loves it, he loved it when he was three as well. His faves were the water parts and the space things. My Older kid loves the half to the right,more educational but at three my younger one skipped that altogether. You might not do it all in a day but I agree, go early, we do the same and there's usually only a few others, it's really empty!
I went a couple of weeks back with my 3 year old daughter. It's well worth a visit. She's been before a few months back, loved it again and i think still hasn't exhausted everything there is to do there. I would advise you get there early...i'm an early riser so we were there as soon as it opened and had the place almost to ourselves. When we left around 4 pm it was getting very crowded.
Enjoy.