We check this website, now tripadvisor.de is up and dont blocked for our system and other users of the Internet.
So, answer to question: Is tripadvisor Down Right Now? - NO! tripadvisor is up!
If you have problem with access to site tripadvisor, and domain tripadvisor.de is not avalible.
Clear browser cache and/or try other web browser
(Chrome, Firefox or Safari).