I'm a guy who, once he's hooked, could care less if a show "loses its luster". I still love The Office, I still love Dexter. Having just gotten Showtime and HBO for the first time in my life, I'm hooked on Game of Thrones (reading the books now), Shameless, Boardwalk Empire, and Homeland. Although I noticed some of its glaring flaws, I liked the first season of Terra Nova, and will continue to watch it because I love the premise and it has so much potential. The Walking Dead is a must watch, and the first episode of House of Lies was hilarious, in my opinion. Looking forward to Alcatraz next week.
But again, I'm a guy who's easily pleased. I rarely leave a movie theater disappointed, and am always highly confused when I get home to see Rotten Tomatoes reviews after I see a movie I think is really good.