According to Reddit, there is a way to enable the aero look (blur) on Windows 10 Insider Preview for those of us that didn't get it in the 10074 build. Some people got the Aero look, and some people didn't. So, here's a look at how you can get the Aero look (if you want it). Redditor skittles92 found this work-around:
"Seems some didn't get the aero look "blur" . If you want to enabled just run Regedit and navigate to HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\themes\personalize and set blur behind to 1. There is also an option in the theme color settings though not sure if it will show for non-blur previewers. enjoy!"
Microsoft is conducting a little A/B test in build 10074, and enabled the new effects for 50% of Insiders, but the other 50% won't see it unless they enable it. The blur effect is not yet present in the titlebar yet, but will likely be present in a future build of Windows 10.
It all depends on what you like or don't like and what kind of hardware you are using. Let us know what you think about the Aero (blur effect) in the comments section.