I only have brief personal experience with DPT-S1 web browser.
The DPT-S1 browser is fine for text/photo news pages. Tried google news, Wikipedia etc.
However it was unable to play youtube (presumably because of lack of HTML5 video support). The youtube video pages loaded with the preview images but video would not play.
Again, playing videos is not something that e-readers are meant to do but I wanted to try it anyways.
The build quality on the Sony is excellent and it is truly a joy to hold.