This is probably a long time coming, but I think it's safe to say that I've had a bit of experience using this so I can safely review it. We bought this unit around mid-2013, via AliExpress from a very-Chinese-sounding vendor - the instructions are awful. If memory serves, we paid about $400AUD for the whole thing.
The unit itself is the Chinese clone, and while apparently the quality of these is very hit/miss ours has been excellent. It's been tossed around in a plastic container in the back of my van for three years now, the cords have been slammed in a door once or twice, and the whole thing still works first try nine times out of ten. Indeed, the primary let-down seems to be the extremely cheap USB->RS232 adaptor and getting it to play nicely with VirtualBox.
The round MB-style OBD2 connector doesn't appear to lock to the socket correctly, but we never used that anyway - it'll stay put just fine without it. It came with a full assortment of other cables, most of which I never use - we solely use the round 20-something pin connector and the D-shaped OBD2 connector when Dad had the NVC3-style van.
I was going to use my grandfather's old Telecom toolcase, and buy some foam to cut holes in to protect the thing, but never got around to it... and as I said it's taken a kicking and keeps on ticking.
The software it comes with is pretty sketchy. I know better than to run software from a chinese vendor (the OBD2 dongle I bought came with a mini-CD riddled with viruses), and since it was just a VMware image I went and sourced VMware player myself.
It comes with a USB hard drive (without an external power supply, so care must be taken connecting it to cheap netbooks etc) with an XP image of what looks like the exact tablets MB use - the default wallpaper demonstrates not to use pens, screwdrivers or other metal objects as a stylus. I suspect it's been through a few hands, and potentially picked up some malware as well, as it's pretty slow even on modern hardware (I run it on a Core i7 laptop with 16GB RAM, giving the VM 3GB RAM and four cores, and it's still bullshit slow for an XP VM) - so I disabled it's network access as well.
The VMware image was a bit of a pain, so I ended up converting it to a VirtualBox image sometime around the end of 2013, which allowed me to get rid of the idiotic BIOS password and other stupid mis-features and once it's taken its considerable time to start up it works rather well. I had considered attempting to clean some of the suspected malware off, but I didn't want to break the VM image and now I have room to make snapshots of it, I decided I don't really care.
The WIS software is very handy, with the exception of naming even things like compression testers as "Special Tool 12345" it walks you through most of the diagnosis.
Everything a MB shop could do to these vans in the early 2000s, you're able to do if you can work out how to do it. Unfortunately, that includes things that are potentially destructive in uneducated hands, so I've been filled with some trepidation to mess with too many things (particularly things like gearbox re-learns, which I suspect my van could use as every so often it jumps out of first if you don't let it sit for a few seconds before throttling-up).
I've used it for fetching DTCs and determining what they are, clearing trouble codes and following a full diagnostic procedure. Other things that I didn't blog about included changing the door lock specifications to make up for the fact that the electronic door locks are absent on the rear doors of my van (so now it locks properly on the first button press) and programming new keyfobs to work with the anti-theft system.
If you own a Mercedes Benz and don't have a relationship with a good mechanic, I can't recommend one of these enough really.