This is my third machine and couldn't be happier.  Went from a 21.5" to the 27" Retina and what a difference.  Use a lot for work filling in applications and the size and detail of the new machine are amazing.  Have had some intermittent software glitches so will have to monitor those.  Overall I love this machine and Apple.Edit:  After having the unit for 1 1/2 years my perspective has changed considerably.  After having virtually no problems with my previous Macs I can't say the same for this one.  Periodically does random things, powers down, lose control of keyboard, desktop icons disappear etc.  Took it to Apple and of course they could find no issues.  Their only recommendation was to erase absolutely everything on the computer and rebuild it.