Pros
Coming from a large corporation, there was little upward mobility with rare opportunities to interact with different functional groups. Individual contributors were naturally siloed to work on specific tasks, and it became frustrating trying to expand my skill set and get more exposure to industry knowledge. I wasted a few good years of my career working in a comfortable, but annoyingly complacent environment. Supermicro is the exact opposite. You have free range to approach new opportunities and by necessity, you need to be quick on your feet and take on multiple roles from the get-go. It's a $1.5B company with almost 2000 employees, but it has a start-up mentality and a flat reporting structure that allows it to innovate or adapt more quickly than any other company I've ever worked with. It's also never had a quarterly loss meaning job stability is rock solid. But for ambitious individuals, job security is the last thing to worry about, and opportunity should be the main focus. Hard work and aggressive ideas are highly rewarded with individual recognition coming frequently from the CEO if you're doing a good job. Once you build momentum, it is infinitely easier to get promoted, obtain raises, and build your own team compared to working at a large corporation. If you want a comfortable, stagnant job, then I would recommend going with an established, large corporation. If you're willing to chase opportunity at a company that's growing exponentially, this is a great place to be.
Cons
The start-up mentality comes with its drawbacks. Processes are lacking and the internally developed software is ill-fitted to support a growing company, so a lot of tasks are manual and error-prone. This presents opportunity to improve these processes, but that's only if you have the time and energy. Internal training is sparse and there are no tuition reimbursement or external training options, so you need to be highly self-motivated to learn on your own. There's also a large delta between management styles and capabilities for different groups, so it's important to interview the managers during your own interview to make sure you end up in a group where you'll receive the proper support and encouragement. There is also an over-emphasis on face time from management; more focus should be on the end results of the contributor rather than how much time they spend at their desk.