Pros
It is small enough that some employees have been able to do interesting, entrepreneurial things, in spite of the culture of fear. People are very passionate about the characters, brand and stories. It is a great feeling to participate in the communal parts of the company - the friends and family film showings, and the Thanksgiving Parade Balloon. Lots of people have statues of their favorite characters decorating their desks. The relationship with Disney gives Marvel access to a lot of resources and has significantly improved the benefit structure for Marvel. A surprisingly diverse workforce (upper management excluded). It may be the best place in the world to work if you want to go into IP law.
Kontras
The biggest challenge for Marvel is its culture of fear. There are few lines of communication up and down the management chain and so people are incentivized to not do the wrong thing rather than try new things. Employees are looked at as liabilities rather than assets, which is unconscionable for a company that creates intellectual property as its only product. Marvel's reputation for stinginess is legendary and deserved. Amenities that are considered basic no-brainers at most organizations - coffee, office supplies - are not provided at Marvel. The less said about the bathrooms, the better. People are often not set up for success. Duties are piled on employees without thoughts about long-term support for their roles. There are not clear pathways up the ladder and senior management roles are generally hired from outside, so there is very little cultivation of talent inside the organization.