As in aesthetically beautiful? Absolutely not, the interface is dated. Stable? of course.
I don't think the interface is dated. The interface is still very practical and in many ways a lot more practical than Windows 8.1 and 10. Windows 7 can still handle practically any sort of Windows user from the heavy gamer to the ones who do heavy video editing and even some programming.
As for its beauty, yes, I meant aesthetically beautiful, to me, Windows 7 is still the most beautiful OS by MS, in second place, in my opinion, comes Vista then XP.
When it comes to visual and interface I believe what happened with Windows after 7 was that MS tried to adapt to the tablets and phones interface and still have the usability and beauty of Windows 7. So far, I don't think MS has achieved it, Windows 10 still looks and feels more like a phone's OS than a desktop or laptop OS.