Having never really been a reader of this genre, in the past few months I've read the original Bourne Trilogy followed by these books in quick succession. Upon completion of the original trilogy I browsed the reviews on this website and I have to admit I was put off these books slightly, and now I've finished the books it's fair to say that many of the reviews make many good points. Van Lustbader pretty much severs all ties with the first trilogy within the first few chapters of 'The Bourne Legacy' and almost immediately you can sense Bourne is a different character to the one that had been developed in Ludlum's books. As well as this some of the plots are ridiculously far fetched (the Lindros story in Bourne Betrayal I found particularly difficult to believe. As well as this there is the issues of Bourne's age, must be getting on for 70 by now!!
However despite these negatives I found these books to be extremely enjoyable, the stories move quite quickly so you never sense that you're just treading water, the plots are exciting and you don't really know who will turn out to be good or bad until right at the end. To use a very cliched term they are real page-turners, I read these far quicker than any of the books in the original trilogy which I found did move a bit too slow.
To summarise if you're looking to a direct follow on to the original series you may be disappointed, but if you come in with an open mind and embrace the story you're in for an excting read with twists and turns a plenty.