As I pointed out in another similar thread:
I created this account just now for one reason and one reason only - to echo this sentiment that this UI has got to be one of the most disgusting UIs I've ever seen.
No Windows Aero
White title bar is just butt ugly and completely out of place with the greyness of the rest of the UI
Bottom grey bar is different grey than the left vertical bar's grey, in addition to being wasted space
No options to customize the UI in the settings
Solid colour buttons and solid colour background in general just look simplistic and lazy and 1990s
Title is centered rather than on the left, next to the program icon
Close button not flushly in corner
"Online help" button removed
Registry button used to use the Windows registry icon (a 4-sided 3x3 Rubik's cube, sort of) but now uses a generic four square icon which was completely made up and corresponds to nothing whatsoever, and the icon next to the "Registry Cleaner" header uses NINE cubes rather than the four in the left-hand icon!
UI does not meet user expectations based on 1-2 decades of standard convention in so many ways:Items in the main Options window (e.g. dropdown boxes, checkboxes, etc.) inconsistently sometimes respond to mouseover and sometimes don't
"Windows/Applications" tabs make the selected tab smaller than the unselected tab
Lack of scroll bar center notches (or similar long established conventions) makes it ambiguous which portion of the bar represents the current scroll position
Fuzzy light grey text for checkbox items makes it seem like they're greyed out (unselectable)
Grey buttons on the right side in certain options menus, along with dull grey obscure text, makes them seem unusable/unselectable
Convention-defying checkbox categories (System, Windows Explorer, etc.) obscure the ability to click the category icon to select all items within that category (ditto for results window)
Resize dots on the bottom right have been removed, obscuring the ability to resize the window
It's important to emphasize that most of these problems are not matters of aesthetic preference, these are convention-defying changes that completely throw out the window everything that's been established from nearly two decades of UI and UX convention and make for a confusing, distracting, difficult, annoying, and anomalous user experience.
CCleaner 5.0 will make a fine addition to the PowerPoint slides of experts who illustrate to programmers what sort of UX/UI disasters to avoid. Perhaps the CCleaner developer(s) responsible for this train wreck would like to attend such lessons.