I can't say to someone, press the green button to maximize the program. I can't say to someone, press the red button to close it.
They're all grey, and similar shades of gray, with slightly darker shades of gray inside that's hard to tell which is which.
Now, I know which one does what because I've been using my Mac for a while. However, to a new user...
This interface seems like it was made for expert users with no regard to the laymen user.
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I program, occasionally... I have a friend and guru who taught me how to program. The thing is, my guru thinks like a programmer; He has a hard time thinking like a non-programmer.
He'll create a program where the interface is minimal, and simple for him to use. However, his client(s) will often ask him to make it easier to use. Then (he's been fired from projects on occasion for this) he'll say something like, "It is easy to use." or "What's not to understand? It's all right there."... Or something to that effect.
The thing is, he's looking at it as an expert, who understands computers, who understands the program he wrote, and he likes things a certain way.
However, for someone who's new to computers, new to his program, and doesn't understand every line of code that went into the program, the program is confusing.
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I feel like Yosemite is ugly. I don't like how it looks. I've also found it to be confusing for my mother to use. I think those who like Yosemite are experts with Macs. They know what the three buttons on the upper left do. They know what options exist, and they can figure out where to find them and find their way around.
To a new user though, who's afraid to dig around because they think they'll break the machine, and can't tell what the icons mean inside the circles and know that the one on the left doesn't mean to make the program bigger but in fact closes it... the grey circles, the menus... its all confusing for the laymen.
Red, Yellow, Green made sense to a new user. They made sense to everyone... At least, everyone understood that Red meant to close a program and green seemed safe to touch because it was green.
Yosemite is not just ugly because its flat. Its ugly because it lacks color... And if you want less color, you can go into Dark Mode.
Sure, sure... Looks great for those who know what they're doing. What about grandmother's and young children? What about people who've never used a computer before, or rarely have?