I've checked Eleventh Hour's ratings occasionly on Zap2it and the show's fast national ratings have been consistently around 7.0, which is good for a new show. The Mentalist has been getting very high ratings for it's opening season. Yet I didn't watch it's first episode all the way through. Didn't like it at all. Yet Eleventh Hour reminds me of The X Files and I loved that show.
I do hope Eleventh Hour is renewed for a second season. It's only just starting in the UK next Wednesday (8th April).
Maybe the makers of Eleventh Hour could do a crossover with another CBS show in it's second season? It's highly unlikely they would do a crossover with a show on a different network.