Yes, cranberry juice is very healthy. A study conducted by Dr. Joe Vinson found cranberry juice was beneficial for the heart. Drinking three glasses of cranberry juice a day raised the levels of "good cholesterol" and increased plasma antioxidant levels, thus reducing the risk of heart disease.
(Vinson cited in Newswise, 2003: http://www.newswise.com/articles/view/?id=berry.acs)
In addition to the benefits for the heart, cranberry juice can also help prevent urinary tract infections and is listed among the top 10 antioxidant beverages (see "Bladder Infection Frequent Painful Urination" and "Pomegranate Juice #1 Disease Fighting Antioxidant" below.