So the main thing it seems like it is able to do it take very granular song direction. The 4.0 model didn't stick very well to song direction. It "might" put a "bass drop" where you wanted it, etc.

Seems like the new 4.5 both listens to more nuanced song style descriptions as well as in-line direction better. Still not perfect, but it is an improvement. It's pretty incredible.. it is a huge improvement. Take a look at this example (It does have some errors, like a heard it sing one of the sound directions): https://suno.com/s/xaJNWNZSH17wAano

This is going to open up a lot of creativity where while you are still often at the mercy of the random number generator, you can really shape the song more.