In the past, upgrading to the next release has been a sore spot for users of Linux Mint. The main release (based on Ubuntu) ironed out this difficulty with Mint 17 LTS (Long-Term Support).
Linux Mint Debian Edition is, as the name indicates, based on Debian and has only had 2 releases. Previously, LMDE 2 "Betsy" suffered from the no-in-place-upgrade problem. Chief developer at Mint, Clement Lefebvre, has written a tutorial describing how you can now update from LMDE 1.
As Silviu Stahie notes at Softpedia
Don't hesitate to connect to the IRC while performing the upgrade. One important note among the warnings: Make sure to disable Romeo prior to upgrading. Cinnamon 2.6 and MATE 1.10 will hit it very soon [but] they're not fully stable yet. If you want to test them, it's better to enable Romeo post-upgrade so they don't interfere with the upgrade.
(Score: 2) by bob_super on Wednesday May 27 2015, @03:41PM
[posting this from and LMDE2 machine]
I care for a simple reason: my new NUC has HD6000 video, which is not supported by regular Mint Cinnamon (which powers all my other machines).
That said, I will delete LMDE2 the minute the regular Ubuntu install image comes with a kernel that supports my NUC. Why? Because it's still running video in software mode as I can't get it to properly install the proper intel video driver (I know that driver works in Ubuntu, but I can't install Mint because of the wrong kernel in the ISO). LMDE2 also has a few quirks which are handled differently (properly, for my use case) in regular Mint.
So I'm waiting a few weeks for 17.2, and then I'll join the ranks of "who cares about LMDEx, it's one of those sub-distros which doesn't work right". But at least I will have tried it, courtesy of having a more recent kernel (which ubuntu also has, but no apple-wannabe launcher for me).