Sometimes, sometimes not.
There are some really good online programs out there (see Harvard, UC Berkeley, Berklee Music, Oxford, UMass, etc.. who all teach online)
There are some really bad online programs out there (see any list of diploma mills)
However, there are some really bad not-online programs out there (see any rankings list) and some really good not-online programs out there.
Whether a program is "good" depends entirely on the college and not on whether it's online or classroom.
There are over 4000 colleges in the US and one is ranked #1, another is ranked #4000 -- the #1 (US News) just happens to teach online. http://www.extension.harvard.edu/2008-09/DistanceEd/