The next feature that attracted me is the new "Activity Monitor".
What I found most useful is the section that shows "Recent Expensive Queries". One of the tasks that I do quite often is the optimization of "bad" queries or even "well written" queries that does not perform well enough. This panel of the activity monitor seems to be a good tool which readily shows me the stuff that I need to work on.
Missing Index hints in Graphical Execution Plan
Another change that I noticed instantly is the addition of Missing Index Hints in the query execution plan.