Do you like butterflies?
Do you like them enough to spend $20 or so per head to see them?
If the answer is yes, I suggest going during the 8 months of the year that are not summer. They "said" it would be around 80 degrees / 80% humidity inside the butterfly area - there's no way it was cooler than 90 in there and yes, the humidity was ridiculous.
The 3D film they show is interesting (migration of the monarch) - and the staff is helpful / nice enough, but it was just so dang expensive.
I went with my three year old niece, and she did get a kick out of it, but certainly not something I'll go back to on purpose.
I understand it's expensive to import all the pupae - and there were certainly some exotic and beautiful things to see, but for the price I honestly expected to be wowed more.
In summation, don't go between June and September and check online for coupons / discounts before showing up to ease the sting of the cost.