Historically it had a horrible interface and the devs denied that it mattered. Then they finally listened, completely revamped it, and much of the argument against Blender was instantly gone.

That isn't to say its interface is perfect. But it actually is perfectly fine now.

My experience: The original interface was something that I learned, used for a bit, then I stopped using it for a while. When I came back, I found I had to completely re-learn even the easiest bits, despite it not changing at all. This happened multiple times.

With the new interface, I learned it once and every time I've gone back, I've remembered basically everything I needed to use.

You'll find holdouts that still hate on it, but they do it blindly and often based on the old UI, instead of its current state.