Dr. Sommer is a nice enough guy, but he often doesn't explain everything his paitents need to know. What is nice is that if you have any issues he is quick to refer you to a specialist within your HMO. Since many HMOs won't let you see specialists without a GP's recommendation this is very helpful.
It is difficult to get an appointment with Dr. Sommer (it is not uncommon for weeks or months of wait) and almost impossible to get an 'emergency'/sick appointment. He always seems to be running late and if you go you're best off making the first appointment of the day so that he isn't already behind schedule.