Very nice zoo, with many interesting things to see...

Very nice zoo, with many interesting things to see, like the mixed-animal African exhibit, with good viewing locations/angles.
Good gift shop.
Many of the animals seemed content in their enclosures, which usually gave them a bit of room to roam and things to do.
Hogle is big on opportunities to spend your money. I'm pretty sure there are more cafes, food stands, dipping-dot sellers, souvenir stores of all sizes, rides, etc., than there are exhibits.
The whole ends up with an urban, squashed, commercial feel, but it's very nice, anyway.
Good bit of parking across the street.
Expect a crowd.
My OKC zoo pass got me in for half price by going to the member desk.
On sunny days, better use that sunscreen and wear a hat -- or get a Hogle hat, like I did.