I have visited the place just like weekend and had a good time. The weather being nice and cool made the visit more pleasant. The park has an entrance fee of one dirham per head, with kids below 10 year old (if i remember correctly), free of charge. The train ride that takes you around the park is 2 dirhams per person. The train will make several stops as it goes around the park. Entrance for the museum is 3 dirhams per person. The museum shows informative facts about abu dhabi; their industry, a little bit of history and it shows the city's continuous development. At the end of the museum tour, you will exit on a space or provision for, i guess eating indoors; with tables and chairs. It looks like They offer bikes free of charge, you just need to deposit and ID which you will get once you return the bikes. The park is quite spacious, with several fountains and gardens to walk to; good for jogging or simply for walking and letting the kids play and run. Visitors are allowed to bring in food provided they ensure to dispose it properly. Some of the landscaping is really nice. I like that not so many people visit the place, not as crowded as most parks. Also, I find it cleaner compared to others. They have vending machines available as well. They also have several rides for kids like a small carousel. The place is nothing fancy as amusement parks but it is a good place for family to go for a picnic, where kids can have fun as well. They also have this 'Splash Park' with an entrance fee of 40 dirhams. Unfortunately I was not able to have a look around and explore this area as our visit was an unplanned one. It has a pool with other water activities for kids. Not ideal to take kids on cold weather, best during summertime. It may not be fully renovated / constructed, but I think it has come a long way since the last reviewer's visit. And I must say I have enjoyed and liked the place, and would definitely be back, bringing more kids to play and enjoy the park.
Before even arriving at Khalifa park your experience is dampened by the lack of parking facilities - the back entrance was filled with worker's vans and the front by cars parked to go and visit the surrounding shops (prestige motors, etc.)
The park is currently undergoing renovations so much of the attractions and swing sets are not acceptable, essentially leaving you with a large open green space. There aren't many staff roaming the park, so if you need to ask where the nearest bin are (which are few and far between). Of course, when entering the park they are quick to inform you of the 1 AED price to get in.
The park itself is of average standard, offering little breeze and with the towering city being omnipresent in all of your surroundings, it often feels like you're in some sort of holding room for de-pressurising before entering a submarine or something.
A day at Khalifa Park is not a day out, it's a way to kill a day as you look for things to do in the park. It's like a truck rest stop before moving on to Khalidiya Mall.