I went through three copies before giving up on the 24-70mmL f/2.8. Awful!
Yes, I know that very good copies exist but none came my way. I'll happily pay $2K if the new lens delivers.
The work done in this mm range is now covered by two primes, a 24mm f1.4L II, a surprisingly good Sigma 50mm f/1.4 and a brilliant copy of the 24-105mm F/4is. Still I'd prefer a lighter bag with a stellar 24-70mm F/2.8 doing the work of the three current lenses. The primes are keepers for when they're needed, but for most jobs, give me a good bright zoom any day.