I took the opportunity to check out Mepis 8.5 beta 5 today and was pleasantly surprised at how it is progressing. Keep in mind that most of Mepis is built from the Debian stable branch so not everything is cutting edge. Mepis is using a custom 2.6.33 kernel and boot time and overall system speed is very good. Warren Wooford is very good at building kernels, it is very rare to ever have a problem with a kernel he has built. Mepis 8.5 is still using Splashy, they did a nice job and it looks clean and professional. Splashy is not new technology but it does not suffer from black screens at startup either so it is a good choice for getting the system up and running in the first place. The desktop has the look and feel you would expect and people that are reluctant to make the switch to KDE 4 would feel right at home in 8.5 because it has a classic KDE look.
Multimedia playback worked fine for me in the 64 bit version, keep in mind that Mepis is US based so they can't legally provide every codec out of the box. All of the default artwork looked good, I could see refinements made to the artwork since the last beta I looked at Mepis, they really payed attention to details. The default applications were what you would expect in just about any distribution but that's not a bad thing. There is enough by default to work and enjoy using Mepis and you can always add other packages you want after the install.
If you like a pure Debian based system with KDE 4, you will probably enjoy Mepis 8.5. I will be looking at the final when it is released.
Edit: Mepis 8.5 worked on my Intel system fine but the desktop failed to load with another system with an NVidea GT 200 graphics card after installing the latest drivers....