Preview's "modern" file model which forces you to duplicate files to work on them and then automatically creates files on the filesystem with a name you don't want and you then have to go and clean up.... annoying. A lot of non Mac monitors (I have two HPs at the moment) are not very sharp used with a Mac. Apparently only Apple monitors work well with MBP - this could be balooney by anti-mac it people, but the fact that the monitor is not sharp is a fact. With XCode the fact that you have to download the whole XCode when you just want Make for example, and it comes with its own version of Ruby, etc, and it causes havoc if you have installed your own version of Ruby. brew is good, but luckily certain core unix tools only seem to come with XCode