Me and my good friend have been playing it all day, only got a disconnection an hour ago due to the servers under going maintenance or something. Great game so far, there are some things missing I would have liked to have seen brought over from Diablo 2, but all in all it's a great release. I've not encountered one bug yet, not saying there are no bugs, but it's been smooth all the way and we are about half way through Act 2.
The Acts most certainly take more time to complete which is a good thing, can obviously be done 'quickly' i.e just running through only killing what you HAVE to kill, but it will still take longer than Diablo 2's Acts. Normal mode so far is very easy, which I expected, considering it always was pretty damn easy and especially more so they now have the Inferno difficulty after hell, which I am looking forward to.