Pros
It's a startup. You will learn and do everything in the business. It's in an niche and emerging field like AR, VR etc. I got a lot of exposure to marketing, vendor management, creating legal agreements with partners, hiring and team organization, and a whole host of other things. Work from office. That means when you leave you're off work. Good work life balance. People are nice and supportive. You actually make good relationships with people you work with, because you meet them everyday. Smaller team size, means you will be recognised for your contributions. Growth: this is the big one. In a startup it's either grow fast or get fired. Those who stay here and do well, get well rewarded financially as well as in career. But if you don't contribute you may even get fired. This is a pro for hard workers, but a con for average people.
Cons
Timings for work are quite strict. Monitoring of employees is done to see their time input instead of looking at work output. Leave policy has old rules like sandwich policy, which doesn't really make sense. Leaves are accrued instead of given at the start of the year. No work from home policy is there, which can get difficult in certain cases. It's difficult for you if you are an average worker (see the last Pro).