I had a medela mini electric, and used it 2-3 times a day for at least the first 8 weeks. It had an AC adapter, so ran off the power.

That said, it was loudish (not wake up the baby loud, but louder than I had expected) I like the medela ones that they had at the hospital, these are the kind you hire from the chemist, and thats what I will be doing next time.

for everyday use I found the manual medela one (I have a symphony) fantastic, and I also was able to express more effectively using this than my mini electric. They have a new model out now which looks pretty good.