Lack of experienced management - Most of the manager/directors I encounter had noticable little experience on what they were doing. I would say that the barrier of entry has been very low to allow the head count to grow exponentialy. Of course this comes with negative consequences. There is a massive lack of mentorship and solid direction, a very critical aspect when the majority of the workforce has only a couple of years of professional experience.
Undefined expectations - I believe this tights to the point above. When you have inexperienced management, the requirements and expectations that come from them tent to be ridiculous. I'm not talking about tight deadlines nor challenging projects (those are everywhere and are part of most jobs). The expect projects to be completed with out any outlines. Or software to be developed by inexperienced people with virtually no supervision nor support.
Low salaries - While it is great that you can work from anywhere, it also means that the company hires from anywhere. That fuels a race to the bottom when it comes to compensation. The company will aim at giving an average salary depending on where you are from (while trying to lowball you). However, you might be competing with some else who is willing to do the job for half. Also, once you get in, forget about bonuses or significant salary inincreases.
Stock package - This portion tights to the compensation but it should have its own note. While the very early employees (first ~100) should benefit from their stock options, for the rest is not the same. While discussing salaries this will be a sales point that they will try to hammer down. People who have recinly joined should not expect they stock package to make them millionaires. However, they still try to make new people believe so to low-ball their base salary.
Overall not a great place to learn nor earn.