[Dami]

I mostly use HL to update sheets between games. As a GM, I did regularly take a laptop and ran combat with the Combat Manager for a time. While it helped a lot with initiative tracking, the delay to change monsters, record mass damage, etc between combats was more time consuming than I liked, and the laptop itself took up more space on the table than I wanted. Table space is valuable with 6-7 players. I've gone back to just using it between sessions.
As a player - I took the laptop for a while, and found that was great for just running one character. All my information was handy and when people wanted other stuff like spell descriptions, equipment, etc I generally got to it faster than someone with a book.

If I had a tablet or ipad, I'd use that all the time as a player. I do prefer to roll my own dice, not use the built in roller.