If you are going solely for WWoHP, you may be a bit disappointed. WWoHP is honestly far too small, and this is coming from a giant HP fan and a Universal Annual Pass holder.
It is hot, and the traffic right now is peaking there - even during the week.
If you have no plans to return to FL anytime soon, then yes - do it.
However if you plan on returning to the state soon and not in the summer, I would wait until then.
I would suggest you temper any huge expectations however, and realize it will probably take you half the park hours to ride the 4 rides HP land offers.
I am in no way saying it is not worth seeing, it is my favorite thing @ the Universal Parks. I am simply saying that if you are indeed a big HP fan, you may feel as though it is a bit lacking.
MAKE SURE YOU TRY THE BUTTERBEER! And take home a bottle of Pumpkin juice for the cool souvenir bottle.