I've been using the Flint 2 as my main router for months, and so far, I'm very happy with it.
Everything works fine, including the Wi-Fi. So far, no disconnecting problems or other related Wi-Fi issues (but other people seem to had problems with this).
The wireless speed is actually amazing. I get almost 1Gb download and upload from my PC while on a wireless connection (I have a symmetric 1Gb ISP connection) in my office, about 10 meters away.
My previous 200€ ASUS router could not do that.
This is not completely true.
You can create as many as you want with the advanced mode, LuCI. It's a more complex process, but there is plenty of documentation on how to do it.
It is true that you only have 4 SSIDs if you are only using the GL.iNet GUI, but many features are available in LuCI.
There is how you can do it while using SSH (a response from a GL.iNet Staff):