Giraffe is just a brand, not a theme. They usually have an enormous fibre glass giraffe outside though, Didn't yours?
TBH I don't know quite what a Giraffe theme would be, but most of their retaurants I know of now are Tesco cafes where they have stopped having cafes.
They are not the best, coupling a restaurant environment with cafe at best service, but if I were you I would have googled before going there.
Traffic is always bad on an easter weekend. I spent an hour and a half on Friday getting to a local garden centre on a main route less than 5 miles away to buy a new bird feeding station because I didn't have enough room for the amount of goldfinches visiting. It was worth it.
Same applies for the Wacky Warehouse or whatever it's called. When it's that busy 90 minutes is more than enough. Kids feed off the adrenalin from the other kids.
I would call it a successful day.