This is a -huge- thing for some folks.
Have a colleague who does some light pro photography (i.e. weddings, concerts, etc.) I wouldn't call him a Canon zealot or anything, although his first comment at my Sony was 'Well, it's not a Nikon so I can still be your friend.'
We were showing each other shots and he was amazed at what I was able to produce with an e-mount. So he decided to give it a little spin.
All the feedback was around 2 points:
- It took good shots, but.
- Everything was so unfamiliar to him that he missed shots due to not being able to find anything.
Some time later I ran into him again; he had tried Sony cameras a few more times but just couldn't get comfortable enough with the layout.
(The Sony layout -is- kinda bad, even if it's what you've learned on.)