I have comand, as a sat nav it is very poor compared to my TomTom, which can be updated over wifi without connection to a computer. Mapshare updates are free and can be done everyday, as can speed camera, maps are updated every quarter free of charge for as long as the TomTom is still supported by them.
We had major roadworks on the m/way system completed over a year ago and despite comand maps being updated recently, they are still showing the old road layout. The TomTom had the new road layout on their map with a couple of months of completion.
As Headhurts says, Comandonline are the people to speak to. What they don't know ain't worth knowing.
COMAND brings together infotainment, phone, navi etc into one combined, synchronized package that's really intuitive and easy to use. Even the early ones (and I have the original COMAND 2.5 of 1999 in my CL) is a good system for today, if one discounts the user interface is stuck in 1999 (no joystick just a twiddle knob).
I would very strongly suggest that you look for a car with COMAND. In fact with as many toys as possible.
I have COMAND in this car, but in my previous 2011 E220, I had Audio 50. The Audio 50 version had nav, radio/CD, media, aux input, all of which worked fine and were integrated, in that when navigating, it muted the radio for nav commands and when I was on the phone it muted everything else and everything is controlled through the same buttons etc.
The COMAND seems much more modern, but that could be because it is 4 years newer! Unfortunately, I haven't experienced a 2011 COMAND, but my mate has a 2017 C350e with the non-COMAND nav etc and it seems similar to my new one (although I've only had it two days!). The main difference I've noticed so far is that my Linguatronic controls everything, wheres his only does the nav.
The first 204's had Comand NTG4, but following the facelift (MY2011) changed to NTG4.5. Easy to tell which, as NTG4 has a pop-out screen on the top of the dash, whereas NTG4.5 has the screen permanently visible.
One wrinkle with NTG4 - early cars (build date pre 11/2008) had a small NAV partition on the HDD so they can only be updated to 2014/15 maps. Later updates will try to load but stall, at which time you are VSF!
Updating NTG4 is easy as the DVD's are re-useable so can be bought "second hand" on here, t'other side or Ebay, just make sure you get genuine MB DVD's. I've done mine a couple of times for rather less than the £150 cost of brand new DVD's.
Updating NTG4.5 is another matter - you need a PIN from the MB mainframe specific to your car/VIN (can only be obtained by linking you car to the mainframe!) as well as the DVD's, so it's main dealer or indie like comand.co.uk rather than DIY, and will cost at least £100.
I'm fairly happy with the comand satnav despite all the comments above, and particularly like the scroll wheel scale change easily done while driving - much easier than changing scale on my TomTom Go 6000 in t'other car. I also have the phone prep and cradle in the centre arm rest, and find the hands-free in the car superb.
Check that the scroll wheel actually works by rotation, it has a flimsy plastic shaft that is known to break, an aftermarket aluminium replacement is readily available, fitting it is a DIY job for some or if, like me, you're not happy to DIY it, my local ICE mob charged me £120 to fit it (the shaft cost $49 from Germany).