2. Connecting sources a breeze!
With other dashboards, I've (almost always) had issues with connected external data sets.
The process of actually connecting data sources couldn't have been easier (disclaimer: I've only connected Google Analytics data). This is in relation to other third-party dashboard solutions where I've found it much more cumbersome to connect data sources. It shouldn't be surprising given the connectors are all under the Google "eco-system".
The business implication here is that it makes creating dashboards much easier for anybody. This is only good news for those that may not have the "technical" skills that may have been needed with other solutions.
3. Ability to customise "look & feel" of dashboards are endless
My personal philosophy with dashboarding and reports is that it (along with being meaningful, of course!) must aesthetically look appealing. It is my experience that reports that look great have more chance to have attention spent on it by your target audience (unless your target audience are finance people / accountant - in which case, just give them tables full of figures!)
Google Data Studio not only made customising the look & feel very easy - but the options that it gives is almost endless. This is fantastic when analysts think about dashboard layout and strategy around meaningful information to report on and how (pie chart, table, line graph etc.) this information will be represented.