The change from 2.7 is both big and small depending on the perspective.
Going in I was worried that I would need to relearn a lot of things, but while there were some big changes (like the ui, scripting, eevee, etc) I was still able to navigate things easily with only occasionally needing to look something up. I still think the old ui got way too much criticism, but this new ui is better so hopefully this will please everyone. All in all, a really good .x update, but definitely not a major one like 3.0 will be.
I am also kind of struggling with the new rendering engine. While it's way way faster, the renders are different enough especially with certain things like shadows and transparency from cycles that I am on the fence about what my future workflow will look like.
Blender is such an amazing piece of software and probably one of the most successful oss applications out there. This is another really big step forward for it.