This new tab allows you to view your Google AdWords account data by different dimensions in time (very hard to resist a Dr Who joke here...). For example selecting the All-Time date range and choosing the Quarterly Dimension brings up all your account data shown quarterly. You can then sort by the familiar metrics (clicks, impressions, conversions etc…). So next time your client asks which was our most successful quarter to date the answer is merely a click away!
Go and play and try not to wonder at it’s simplistic but practical charm! (click to enlarge the screen shot)
Update (Aug 2011)
Yes, I am updating this post over a year later...
So the AdWords Dimensions tab is all grown up now. Google has adorned it with features such as grouping (Time and Conversions) and added a plethora of new dimensions for you to play with.
Some of the new arrivals in the last 12 months have been the display'centric Demographic and Automatic Placements.
Geographic is a useful tool for any international campaigns you're running, allowing you to view performance between countries without having to run a cumbersome report in the new Reporting Centre (it's so bad!).
However the most useful addition (in my opinion) to the already neat little tab has been the introduction of conversion metrics and revenue. Adding a much need element to this method of analysis.