Great individual contributors poorly managed
Pros
Tesla attracted some really great individual contributors to build Model S. They get five stars for building a stellar product, and +1 more for opportunity to innovate in the automotive space. (Yes, I know that's 6 but they lose 4 for crappy management). The biggest plus for Tesla is that the CEO is willing to make mistakes and take risks. Tesla is also willing to incorporate relatively new technologies into their products. It is a company challenging the automotive industry to "do better" by setting a high bar for quality and features. This is worth involving yourself in, IMHO. So there are some excellent opportunities there.
Cons
The company's management and HR policies are awful (-4 stars for this). They sometimes promote managers from within, but engineers frequently have exceedingly poor people skills, at least they did at Tesla. To make matters worse, the HR policy uses "stack ranking" and each group is forced to pick one individual as "worst". These people, no matter how skilled, are culled once or twice a year. So if you are great at what you do, working with 4 other great people, one of you is going to get let go, doesn't matter if all are great. This is incredibly stupid! It creates an atmosphere of suspicion and non-cooperation, and psychological fear. Very bad. The work place itself is low rent: IKEA tables and chairs. Big, open, very noisy space; poorly lit and visually distracting with people walking between long aisles of "desks". It is furnished like a start up, but is a multi-billion dollar publicly traded company. Its bad enough that they tended to avoid showing the work area to potential hires. Tesla is a great place to "come from", but not a great place to be.