So, you probably want to play with all the new performance-related features of the SQL Server 2014 CTP that was just released, such as Updateable Columnstore Indexes, Hekaton, and Buffer Pool Extensions. However, don't jump on the download and try to install it on a machine that already has an earlier version of SQL Server or any installation of Visual Studio. During setup you will fail on two warnings:
A SQL product other than SQL Server 2014 CTP1 is detected. You cannot install this release until the existing instances of SQL products are uninstalled.
Installation blocked due to detection of versions of Visual Studio that install SQL Server 2012 client libraries. SQL14 CTP1 is prerelease software and should be installed only on a clean machine.
In many of the previous versions (at least from what I remember), while running the beta side-by-side with the previous version of SQL Server was not technically supported, it wasn't blocked by setup either. These days you'll have to devote a VM (or machine, or environment) to this type of testing, and be prepared to wipe, rinse and repeat when the next CTP is released. From previous experience I would recommend not bothering to try and "clean" an existing machine by uninstalling SQL Server and/or Visual Studio.
I'll be blogging more about the features later, but in the meantime, I wanted to try and save you some headache…