One thing that you can see right off the bat, is that there are really no visible options to do anything. Mousing over the top bar changes this, and displays the menus.

I have a huge problem with this. For starters it is not obvious that there are menus and window controls (should the window be maximized), and secondly, if I have multiple windows for the same application tiled side by side, how am I really supposed to know WHICH window these menus apply to? Not to mention that, on a large display, the menus can be far away from the actual window.

And then, of course, you have the non-conforming applications. Would it REALLY have killed anyone to create a port of LibreOffice that actually worked correctly with Unity?

Moving right along, here we have the dashboard.

Rather annoyingly, it fills the entire screen and takes over whatever you were doing before. Closing it requires use of the windowing controls (which have a 2D appearance, unlike all the others) even though this is not a window.
The icons are not as big as previous verstions, but they are still unnecessarily huge, especially for a display that isn't running at the world's highest resolution.

I do not understand the hierarchy that is now in place, either. If the app isn't a music or video app, it then falls under More applications. Which makes just about every single app installed by default "another application", and thus destroys the whole point of a hierarchy by essentially telling the user "Here, have all the things, all at once!". There is no such thing as a "custom hierarchy" with this dumb implementation, either.

So I guess it is necessary to browse More Applications, then?
Look at this mess!

At the top we have a list of recently used applications. None of which I have used at all, but whatever.
Below that, we have the list of installed applications. Which is always closed, and thus you have to click on expand every time you open the dash up, bringing the total number of clicks required to open an application to four (Dash→Applications→Installed→<Application name>).
And then below that we have a list of applications you should download. Meaning they aren't installed yet, but you must have them. Uh, what? If I wanted any of them I would go and download them, you don't need to shove them in my face whenever I want to open another application.

If we expand the installed applications list we are greeted by an even bigger mess. Again, Ubuntu has basically just shoved all the things into our face without much of a way to sort through them. Like the Windows 8 all apps page, this list can become a mile long once you install a few applications.
Sure, you can search for an app, but partial name searching doesn't exist, and it resorts to an utterly useless case-sensitive name comparison like every other UNIX-based operating system out there anyways, so it wasn't very helpful to begin with, but you can't even search for part of the application name! What use is that?