It certainly is one of the most imaginative shows ever. The "you can go anywhere, anywhen" is a fantastic premise, and the writers use it to full extent ( most of the time ), all that with lots of humor. The show can even be totally nuts, in a good way ( see : "The Big Bang" or "The wedding of River Song"'s opening ) , and can boast very original monsters : you'll be scared of the shadows, of statues, or even of creatures under your bed or in your cupboard again ! Some of the plots are hits and misses ( too many TARDIS- or screwdriver-ex-machina ), but the writers know how to use time travel elements to break your heart : see "The Girl in the fireplace", the 2011 Christmas special or "Vincent and the Doctor", my own personal favorite.
Happy 50th birthday, Doctor !