I was quite suspicious of it when it was first announced, but an open source RE tool is probably the stupidest place to put a backdoor. Author considerations aside, it’s a great tool, and does pretty well with decompiling.
It's pretty spectacular.
Radare2 has a plugin for using ghidra's decompiler too https://github.com/radareorg/r2ghidra
So you can get all of the terminal level unix like goodness of radare2, yet still get really great ghidra quality decompiler output.
(I believe IDA has a check to stop you from doing this. Cracking that was one of the "rite of passage" exercises back in the day.)
IDA has had watermarks and all sorts of other fancy stuff. The real challenge with IDA was extending the demo to allow it to save databases before they started publishing a working older free version.
I like IDA a lot more than I like all the other tools, especially since I consider the user experience and hotkeys far superior, but the other day I did look at something where the disassembly and decompilation was great compared to other tools(one of the r2+ghidra UIs). I think because flirt signatures were missing and I can't get Hexrays to sell me a new license.