PLoS ONE has now published over 5000 articles in two years of existence.
I see nothing wrong with that although some do.
We'll see which exclusively online open-access journals manage to gain traction.
(One I'm an editor of, PMC Biophysics, from PhysMathCentral, has just started up.)
Of course, the whole open-access experiment may be nipped in the bud if congress kills it, as it is now considering.