Given Mavericks' poor reputation for Apple Mail - particularly with GMail IMAP - how did you find Yosemite Mail?
Honestly, Mavericks mail really made me mad considering I have 8 Gmail accounts (for YouTube before they allowed multiple channels on one login). It was just a nightmare. I tried Mailbox beta, not my cup of tea really. I guess its the fact that you have two options for badging the app. Either:
Show all messages in the Inbox (read or unread) as the badge (I.e. 200 messages in your Inbox would display 200)
Or Show a 1 for new messages, which means no matter how many new messages you have it badges a 1. Rather annoying. I have complained to them in the past (particularly when the iPhone app came out, I wait to use that too!)
Seems fine to me. Only weird thing I've discovered in PB4 is the boot menu is now in black and white, it looks really odd against the normally coloured drive options. Anyone else found this? I don't know if it's deliberate or not.
Aside from that and continuity still not working for some reason its a great and solid OS. Safari is fantastic, HTML5 Youtube & Netflix by default is awesome!
I notice you have a late-2013 rMBP. I have both a late-2013 rMBP and a 2009 Mac Pro and the rMBP is the only one of the two that shows a black startup screen and the background for selecting a boot disk when holding Alt is black as well. The Mac Pro is the same; white. I think only certain rMBPs (late-2013 and later) have this featue, which I kinda like actually. Makes sense too considering iOS now behaves the same way on iPhone 5 and newer (white back/black Apple on white devices, black back/white Apple on black devices).
I wonder if there is a setting to change that would turn this on and off. We might be able to turn it off, but users of other computers I don't think could activate it since I beleive its part of an EFI update that installs itself automatically after installing Yosemite.
So far the only annoyance with Yosemite is the fact that installing it coverts my drive to Core Storage/Logical Volume. I hate that. I'm not sure if the terminal command can be run directly from within the OS, however I installed Mavericks on a small partition, booted from that and changed it back to standard GPT. I have no idea why they did this, but thankfully it is reversible. I beleive it only happens to Macs with PCI-e SSDs (MBA mid-2013 and newer, rMBP late 2013 and newer, and 2013 Mac Pro).
If the Recovery Parition has Terminal (I think it does right in the Utilites menu?) I think it can be run in ther with no problems.