Vantaggi
You'll meet and work with some strong developers that are interested in your growth as a developer. They are willing to work with you to help you become a stronger and better developer. Unfortunately this is despite management. You'll get to work with the latest and greatest when it comes to web development standards. Such as micro services, event sourcing, frameworks etc... Because they're a consulting company, you'll work on many different projects, so you'll learn a lot.
Svantaggi
You will start with well below average pay for the position. Pay raises are standardized for some, subjective for others. Company is often overbooked with clients, so you will be left alone with little to no help from management. You will be chastised by management for asking for help from fellow developers because they are also overbooked. Company is more interested in churning out code than building good sustainable software. Coupled with issue above, this often leads to cutting corners in the interest of saving time. There is no HR, and CEO tends to be too aggressive in the way he talks and interacts with the developers.