With some regret I returned my rMB over the weekend. I thought I'd summarize why...and why I didn't. The rMB was a 512gb 1.2gHz. First, it was not because it wasn't powerful enough. I used it a lot with the programs I use regularly - MS Office, Adobe Acrobat Pro, Adobe Lightroom, Adobe PSE and Safari, among others - and the rMB definitely holds its own. In relatively extreme tasks I saw some slowdown, but nothing that was either unexpected or too significant to be an issue. Second, it was not because of UI lag. I used it a lot side by side with my rMBP and there was no meaningful difference in regular use. I don't game, so I can't comment on that. On the plus side, I really liked how small, light and portable the rMB is. I also found it noticeably more back-of-seat friendly in cramped seating (my use is commuter trains but the same would apply to airplane seats). My comparison is to the 13.3" rMBP, and the size difference is just enough to make a difference. The two reasons I ultimately returned it were that the keyboard didn't agree with me and, after some practical thinking, I realized that there were going to be issues managing using two laptops concurrently. The keyboard - I expected to like it or at least to be neutral and get used to it. In the end, to my surprise, it turned out to be a lot harder to type accurately on the new keyboard than my rMBP or my Apple BT keyboard. This is totally YMMV territory. The other thing that pushed me over the line when i was thinking about returning it was managing two laptops (in addition to my Mini). Not so much keeping files current, but license management issues. Most of the programs I use a lot are limited to two installations, and keeping track of what is activated on which laptop presented possibilities like taking one of them on a trip having forgotten to deactivate/sign out on the other one, which could be a real problem. The alternative would be to move to subscriptions with Microsoft and Adobe, but I'm not ready to do that yet. A third consideration was that I often need to have two spreadsheets or documents open side by side. While that was possible with the rMB, the extra 1.3" (diagonal) of the rMBP made it just a little easier to read the text/numbers. The experience with the rMB did change my thinking about what I want from a laptop, however. I absolutely love the new trackpad, enough to be willing to pay something to get that. Because it turned out that I really disliked the keyboard, getting a laptop with the new trackpad but the old keyboard (assuming Apple may migrate the new keyboard to other Mac laptops soon) seemed like a good idea. And using a laptop with a 512gb SSD after living with 256gb was very freeing (in HDD days, my laptops had 1 or 2 TB of fixed storage). So, result is that I returned the rMB and am selling my rMBP and have purchased a new 2015 rMBP with new trackpad, the old keyboard and a 512gb SSD. TLDR: the rMB is a fantastic ultracompact, but didn't turn out to match my needs as well as I thought it would. I sincerely hope everyone will enjoy theirs.