My brother had one for years and loved it.
Obviously have a good look and check that everything works.
It might be worth getting it checked by a Merc independent as they will be able to plug it into the Star diagnostic system as well as give it a thorough once over and give you a report.
I had one done when I bought my used Merc and it was worthwhile.
There are some very good forums for Mercedes that are really helpful when/if things go wrong.