[Bahamut]

Agree 100% - I only am now starting to approach freelancing seriously after 2 years of development at several companies, and I found I have learned a lot from working with other people. Working with other people means you can bounce a lot of ideas between each other and you can see how others code in code reviews or just browsing their code.

You will never get as strong feedback being a solo programmer - in fact, the feedback will likely be minimal.

[lukaslalinsky]

There is also one other disadvantage of being a solo junior dev - you will often work on very simple things. Complex systems usually require more than one person, and even if you are working as a junior dev who is just assigned tasks, you get to see how larger applications are built and gradually get into the design process. This is not something you get when building simple web apps as a freelancer.