It was the first and for a while, the only, distro able to boot up graphically on my Dell Pentium 4 at that time (probably around 2006 or 2007). I'd burnt a few CDs with other distros before that, including Ubuntu, but they failed that first hurdle. My PC had 2 hard drives, the first contained WinXP and the Data partition, while the whole second drive was specifically there for Linux trials and experiments.
Mepis 6.5 ran really well, and I kept it for a long time on my hard drive, while also starting to enjoy the fun of multibooting. I found 2 other distros some time later that worked well on the machine, ie PCLinuxOS (KDE) and crunchbang 9 (also by coincidence the one crunchbang release based on Ubuntu - I didn't go looking for Ubuntu variants, honest!). I didn't really like Mepis 7 but Mepis 8 and 11 were good. Mepis 12 beta just refused to work on my machine, which was getting older by that time, so I found myself looking for distros with lighter DEs. I continued to use Mepis 11 but also installed WattOS (LXDE), crunchbang 10, and the last 3 really nice Gnome 2 distros - Fuduntu, Parsix (debian testing) and the original SolusOS.
And then, XFCE got much prettier and really nice to use with SolydX and Manjaro. By this time I hardly booted into Mepis 11 anymore.
But what do you know, the 3 Gnome 2 distros all went defunct around the same time (Parsix continued as a Debian Stable distro running Gnome 3, which was too much for my graphics card to handle). So SolydX and Manjaro XFCE became my mainstays (although I was still multibooting).
Until whispers of MX14 began to be bandied around in 2014....
Now my reliable workhorses are MX and Manjaro. SolydX is gone from my (new) machine now. The official edition moved back to a Debian Stable base, and because it sticks really close to vanilla Stable, you don't have the fresh and interesting packages that MX has in its own repo. There's no packaging team. If you want newer stuff you would probably have to get it yourself from Debian Backports or compile it or add the MX repo (I'm guessing it won't cause too many issues). It's a fine distro, but to me it lacks the spark that MX has.
I still multiboot though.
