I have this, or well, a version of. Got it off a friend and didn't have to pay a penny
It's great, and though I agree that printed comics are nicer,I'm not that good a reader and sometimes the small print they put in the balloons i find hard to read, so I love the fact that I can zoom in and out, and I don't even have to use bookmarks or remember where i got up to, it does all that for me.
However I will get the TPB's if there's an arching storyline that carries through the other series such as Spectacular, making it easy to read with the correct issues in one book. God I love TPB's.