I'm not against using an iPad in flight but I think we have a long way to go before it's actually useful. We had some for "testing" recently and it was just a big waste. If we ever get to the point where we don't have to carry both the iPad and paper pubs I would be more willing to go along with it, but at least for us, we had problems with enroute chart resolution and screen refresh rate. Zoom in far enough to make the charts legible and by the time it was displayed you needed to move again.
I did like having approach plates nice and clear, but finding the right one could be a challenge. Also if they were able to go secret that would really push me to the "For" side. Anybody who's ever lugged an Eboard around would probably agree. To answer the original question, I have used an iPad in the cockpit. Once. For the moment, the advantages don't outweigh the disadvantages. Add to that the fact that we can't connect our iPads to anything. We have to take a standalone computer if we go anywhere with the things, "Just In Case" we need to update something. Maybe in a year or two after more work is done on several different fronts it will be great but for now it's just one more thing (two more things if you count the standalone) to get stuffed somewhere in the backseat.