They use code from open-source projects, without following the licensing conditions/crediting its original authors, effectively stealing the code.
They have done extremely shady things, including starting a paid piracy subscription service.
There's a lot more shady stuff they have done, but I don't have the patience to get into that.
It's not all bad though. No one's forcing you to use their shady piracy service, and as far as SX OS goes they have done more good than bad IMO. Their tools are better than the homebrew ones in features, UI and ease of use. They take open source projects and
actually improve on them.
Can't really blame them for not wanting to open source their improvements since it's what's making them money. You are still free to blame them for not following the license.
But try to see it from their perspective, if they had to open source their changes they would have never made SX OS to begin with because there'd be no money in it.
So no one is worse off by it existing, those that are willing to pay a little for the extra features (if they want them) are better off, and for everyone else it's the same as if it didn't exist.
Now I will agree that it would be much better if they got off their lazy asses and actually did their own work instead of copying someone else's. At least Gateway did all their own work even if many times it was inferior to what was available with homebrew. Early on they actually offered something you couldn't get anywhere else and it was only thanks to people reverse engineering GW's code that we eventually got free options in the form of Pasta CFW and rxTools, which was later followed by other CFW. Which is not much different than what TX is doing only in reverse. If SX OS really is made by the same people as Gateway then I guess the homebrew scene got what it deserved in a way.
All that being said I don't really care about the team, who they are or what they do as long as they deliver a good product that's worth paying for. And as of right now, I think they do. I won't hesitate to jump ship and move to homebrew alternatives as soon as they catch up. EmuNAND is the big feature I'm waiting for.