Pros
Arista is a nice place to work for a young engineer. You get more responsibility and learning compared to a bigger company. The coworkers -both seniors and peers- are both talented and dedicated., and are generally willing to spare time to help new people get started in the company, The software engineering practices and tools are geared to make the life of a programmer easy without compromising on code quality. The instances of you getting frustrated with tools, processes and people for being roadblocks are minimal. The management is generally supportive and flexible regarding working hours and time off, even though you are expected to be responsible in meeting the commitments you make. Micro-management is not a problem. Compensation( including stock ) is generally on or above par with the high paying companies in Bangalore.
Cons
Office facilities are seriously lacking, and people who have worked at big companies would especially feel the difference. The paid-time-off offered is very less compared to similar companies. The timelines are aggressive, and you need to put in a lot of hours to get stuff done in time, although you do get a say in deciding the timelines.