Two reviews published this year in Mass Communication & Society deal with these books, and are worth reading, especially the Pan review.
Also, I should mention that some students have found useful Katherine Kramer Walsh's book on political discussion, and a review by Gamson can be found in the latest issue of Public Opinion Quarterly.
Setting the Agenda: The News Media and Public Opinion (Paperback)
by Maxwell McCombs
Projections of Power : Framing News, Public Opinion, and U.S. Foreign Policy (Studies in Communication, Media, and Public Opinion) (Paperback)
by Robert M. Entman
Volume: 8, Number: 4 2005
Volume: 8, Number: 2 2005