So, I really wish that the Devs, would add either a toggle function to switch between UIs or they should improve the UI. I really don't have a problem in how it looks, but, I've noticed that since the UI changed, the program has started to lag a bit. If it sits open in the taskbar, say, for about 10-15 mins, and I do some other work meanwhile, it would then show visual impairments in coming up, earlier there was no such problem. Regarding the improvement, well, Ccleaner is not the first program (in my knowledge) to have adopted to the new UI. 'Telegram' messenger's desktop client too has a modern appearance. The difference that works out is--that CCleaner uses Win8 UI, the messenger uses Win10 UI, giving it a more smoother look.
If, the UI improvements works, then well and good, but in any case, I see more demand to revert back to old UI or to provide a toggle option, I'll be fine with any of them. So please roll out an awesome update next time Devs!!
Thanks for your precious time.