LMDE Xfce is what I have installed on my other drive.
I use Debian testing Xfce as my production OS.
I am an ex Ubuntu dev release tester of some experience. Even used the dev releases as my production OS for a couple years.
All that said I can tell you that even without the Mint menus, which are not in the Xfce LMDE version, this is a much better respin of Debian testing than the way Ubuntu does it.
The last I tested was Xubuntu 12.10. Based on Debian testing as are all Ubuntu LTS releases. Took a whole gig more room on a standard install compared to Debian testing Xfce. LMDE Xfce is only slightly larger on the standard installation.
Ubuntu, what ever the DE, adds a lot of crap and changes the way the file system is used compared to Debian. This makes their system more and more incompatible with Debian packages.
LMDE uses their repo to filter Debian packages for stability. The packages, including the install scripts, are not messed with. Therefore the LMDE install is completely compatible with Debian packages from any of the Debian repos. Using those packages is going to give you some unstable conditions but you can do it if you want.
This strikes me as the perfect OS for someone that is a bit nervous of Debian but wants to learn to use it. The system is set up with packages that Debian will not install by default due to their definition of "free" so that is removed as a potential problem. Default configuration is probably more to the likeing of the new user than a clean install of Debian testing.
Xfce has not been messed with as it is in Xubuntu (added Gnome packages makes Xfce harder to configure there). The Xfce set up tips work under LMDE Xfce.
Really the best respin of Debian that I have seen for the noob.
I keep reading that it is for "advanced" users. I think that has to be the Ubuntu definition of "advanced". They also claim that Synaptic is for "advanced" users.
Coming to linux (Ubuntu 8.04.1) in my 50s with no experience with anything but MS (starting with MSDos) I had no trouble using Synaptic. Don't think I was an advanced user.
LMDE is more stable than 10.04 was on release. More stable than 12.04 on release. Will be ahead of 12.04 when 12.10 is released.
LMDE should, with the package management system it uses, keep pretty close to the Ubumtu releases. The main difference will be that LMDE will be stable.
If you have the space, say 60gigs, install LMDE, Debian testing and the current Ubuntu. I suggest whatever DE base you like. Put them on about 10gig / partitions and share a 30gig /home partition (different user names must be used in each distro).
You will imediately see the difference in size of installs on the / partitions. You will also see the difference in stability between LMDE and the other 2.
If you install the package "apt-listbugs" in the Debian testing install you can easily keep it as stable as Ubuntu. This will also give you an idea of the amount of work the LMDE repo maintainers go through to give you only stable packages from the Debian testing repo.
It is one of those things that you see in practice and wonder why no one tried it before. Seems obvious in hind sight.
Really a great idea.
If you really need the newest packages you can always corrupt the LMDE install with packages from the Sid repo or even the Debian experimental repo.
I would not do that with LMDE myself or recommend it. There are a lot of LMDE users doing just that or tracking the Debian repos instead of the LMDE repos. They like it a lot.
I don't because I prefer the Debian security model to the (basically) Ubuntu security model used in LMDE (at least LMDE requires a password to get a # prompt in recovery mode, unlike Ubuntu that just gives it to you with out one). I like a separate root password. I think with out it you have shaky security.
However, if you are coming from MS to linux, the LMDE system is much more secure. Even the Ubuntu system is somewhat more secure.
Side by side comparission of current releases may cause you to come to a different opinion. While I think your question is a good one, the only way to get an answer that really suits you and the way you work on your box is to compare them for yourself.
This is the LMDE forum. Most folks here are going to prefer LMDE of coarse. I prefer Debian. You may prefer Ubuntu, one of its family members or another distro all together.
Using them, side by side, over a period of time, is the only way to know what you want exactly.
This is why there are so many choices out there in Linux land. Some feel this is a weakness. I don't. I think it is one of the core strengths of Linux.
Try them out. Use the one YOU like. To hell with my opinion or anyone elses. It is YOUR box.
This is my box. I use Debian. I have LMDE on here as I need to keep an eye on it as it is what I recommend for noobs.
I am VERY impressed.
Dell XPS 420 Core2 Quad Q 6600, audigy5.1, Radeon HD 6450 - currently 4 320Gb HDD, Debian Squeeze for secure use, Debian testing for daily use, Debian Sid for fun.