all depends what you intend to do there.....
There will be little water so the falls unlikely to be flowing. Again check with the ranger, I think they close areas over summer - it was very hot when we were there, (compared to Streaky Bay where we were staying) no wind, and little shade. We spent maybe 5 hours in there at Organ pipes, the dam, Panny homestead, Shearers quarters etc. (a 30-40km trip really). I can't comment on the northern tracks or 'activity areas'.
I want to go back again for longer next time, but not in summer.