It seems that creationism's big hitter these days is "Well, there is no known mechanism for an increase in the amount of information held  within a creature's DNA so animals can't get more complex".

I have no problem shooting holes in most of this argument but is there a good reason why they keep returning to it or is it just a bit of clever semantics that makes the question seem unanswerable? 

Is this something that we really aren't sure about yet? 

I am keen to know because I have always found evolution very easy to explain and understand without getting at all technical and this rather throws a spanner in the non-technical workings!