I did a hardcore acclimation when I got mine, but that's because I bought a ton of stuff that day so the effort wasn't just for one critter. I took my 5g fish bucket, put all the corals, shrimp, etc I bought that day in it with the water from the store. I added a minijet and a small thermometer. I then started slowly, over the course of a couple hours, adding water from the tank he went into. All in all there was prob 2g of store water to which I added about 2g of tank water. Then I took most of that mixed water out and slowly added another gallon or so of tank water. Mine opened right up once he walked to a spot he liked and has been that way for about 2 weeks now.
I don't think that all that is necessary (and like I said, I only did it because of the quantity I got and it was time for a water change anyway). It does show that they will open up quickly if acclimated slowly though. I'd say the key is whether his tentacles are poking out when he is balled up. If so, he is just curled up. If they are REALLY bad off, all you will see is their outer covering and all the tentacles will be curled inside. That's just my experience with a previous bubble tip talking though.