If you expect a classic Robert Ludlum Jason Bourne book or a classic Eric Van Lustbader ninja delight, you will be very disappointed with this book. The Bourne Legacy doesn't fit well into either camp.
If you are willing to forget that you have ever read about Jason Bourne or anything else by Eric Van Lustbader, you will probably find this to be a relatively pleasing page-turner of an action novel.
The book shifts in a number of ways from the prior ones. First, this Jason Bourne is always reacting . . . and a little too late. Second, he's vulnerable both physically and emotionally. Third, he unrealistically recovers form serious injury time and time again to take even more abuse. He's sort of like a silly putty man in that sense. You toss him away and he bounces back quickly. Fourth, his long-time co-characters all but disappear. Fifth, an important new character is introduced, Khan, whom you will probably either like a lot of hate a lot. I leave it to you to decide.
Clearly, this book looks like it is intended to launch a whole series of novels based on the events in it. If you think you might like to see an action hero develop in a different way, give the book a try. If you want more of what you've had in the past, avoid this book.