It affects the E7x40, E6x40, E5x40, E5x50, M4800, M6800, E7450 & XPS 13 2015 under Linux/VMs.

So basically Dell took a few months to fix the keyboard de bouncing under Windows and when they finally released a BIOS update they made the situation a lot worse for linux users (keys would appear to get stuck). After waiting a few more months, they finally released another BIOS update to "fix" the anomaly under Linux (they fixed the "stuck" key problem but many users are still reporting a de bouncing issue, see the latest pages of this thread if you are interested http://en.community.dell.com/support-forums/laptop/f/3518/t/... )

There's also a touchpad & trackpoint issue that is still not fixed after more than a year and It looks like a BIOS/EC/firmware issue: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1258837

Dell also broke USB3 support in the latest BIOS update for the E6540 and on the E6440 http://en.community.dell.com/support-forums/laptop/f/3518/t/...

They also released a botched BIOS update (when UEFI netwokrk stack is enabled) fairly recently that necessitated the removal of the CMOS battery in order to boot... https://www.reddit.com/r/sysadmin/comments/2m6u4s/dell_latit...

Also their fan control & thermal management is a sad joke. http://en.community.dell.com/support-forums/laptop/f/3518/t/...

Their BIOS testing process is broken if not in -existing.

So, if you want to buy a Dell machine, just make sure that you know what you're getting into... Once the initial BIOS is declared gold it can take several months to see an issue resolved.