I've got 120k miles on mine and love it. Great fun to drive and very solid.
The M119 engine is often described as "bullletproof" and was also used for years in the S-class.
Be aware that many repair tasks are a bit more difficult with the larger engine in the W124 engine bay. When my starter was replaced (under warranty), for example, part of the front end had to be disassembled to get to it.