Are you talking about this book - Kaplan New GMAT Premier 2013 with 5 Online Practice Tests ?
I did give these tests and found them to be good. The interface is exactly like GMAT. Although Manhattan tests are the best in business and with most accurate scoring, Kaplans' are good too. One gets a few question banks as well with this book and the book itself is good too. So I think it's a good package. It costs nearly $23+$3 Shipping when bought through Amazon but is priced at $40 at Barnes and Nobel (if you are in US). Rest is personal preference. You can also target the free Kaplan GMAT test. The schedule can be found on their website. The advantage is you take it at a particular time, in presence of an instructor and with people across the globe.
