I will always love Paris, personally. If you are a traveler who is focused on hitting attraction after attraction, or aren't really a museum person I can see how it may not be the ideal location. My favorite days in Paris were the ones I spent roaming aimlessly along the Siene and around the Île de la Cité. But I could easily spend a full day enjoying street art vendors and bookshops. My last couple of days were spent with no set destination and I not once would say I was bored. Really is just preference.
I believe it was mentioned above but the architecture is also brilliant; generally just a beautiful city to walk around.
It also makes an easy base location for various day trips such as Giverny/Vernon, Versailles, Lille,..