I think there comparing it to Disneyland and DisneyWorld as from pictures compared at both it is looking tired in places. Disney World has such high standards every night after the guests leave the park cleaned from top to bottom.
Indeed, it's important to remember that DLP isn't just competing with Alton Towers etc. , it's competing with all the Disney Parks around the world. DLP costs roughly the same as the Florida parks, in terms of quality of experience and quality of rides, Florida is a level above Paris.
Even competing with Alton Towers, Disney costs around 50% more per ticket and has fewer major white knuckle rides, you're paying for for that extra level of care and, moreso than other parks, the theming is such a core part of the visit that its less forgiveable than 'normal' parks if the scenery is looking tatty.
Here's a page highlighting some of its issues: http://themeparkinvestigator.com/featur ... and-paris/