TLDR; bad management, lower pay, no HR, product deteriorating.
1. Management and some bad apples. There are guys who just hit on girls on slack like it is Tinder. Outside the creepiness, there are some positions that are filled internally without giving everyone equal opportunity. I'm not really sure what they did, but something is fishy. ShipStation has a setting where all messages in Slack is deleted after 14 - 30 days. You can guess why they set that up.
2. Internal politics. If someone disagrees with your opinion, you will get picked on regardless of the results regardless if your statement is factual or not. This creates a culture of not being able to speak out. This resulted in their terrible "Version 3" of their software. It is like how Microsoft tested windows 9 and just skipped windows 9 went straight to windows 10 because people who used windows 9 thought it was trash. However, ShipStation still released its "V3" because people who drank the Koolaid still thought it was good based on opinions. ShipStation should have done the same and skip their "New" version and call it something else. Their older version is much better and faster.
3. Pay. On the engineering and product side of things, they are paid about 20% less than the average. However, that is balanced out by stock compensation, but who knows how and when that is given out. Not a huge con, but something to note.
4. No real HR. There is one guy who runs their whole "HR Department" however if he goes on vacation what happens? Where do you report sexual harassment?
5. Product. A lot of features are not truly thought out and the product team just rushes their release then the support team has to deal with all of their issues. ShipStaton's one of the biggest competitive advantages is automation rules and they haven't touched that for over 5 years. So they are on a standstill for that feature.