These are great cars. I haven't owned one but I have driven several. The styling is also pretty great. Very unique. There's nothing on the read like the SLCs. These cars were used as rally cars very successfully. AS far as problems, I haven't heard anything specific to the model. Treat it as you would any older Benz. Have it looked over thoroughly. It should be just as durable and reliable as any other Benz.
1995 E420 - retired
1986 420SEL - retired