We didn't plan to book it. We generally don't pay the extra for things like that or the Haven on NCL. The expense is just beyond our normal budget limits.
However, our previous (only other) experience with Celebrity had a lot of issues, so our TA worked with them to get us a free upgrade basically to help entice us back to try them again.
Our TA loves Blu and can't recommend it enough to us, but we like variety, so are looking at the other dining rooms as well.