I wouldn't say either are stellar, they both rely heavily on anectdotes and introuduce "systems" without a lot of backup other than the author says they work. Still both helped me and have increased my confidence in and out of competition. There are some very good concepts buried in both books, you just have to figure out what works for you and what to ignore.
This is perhaps not so much the sports psychology book you are after, but more of a motivational booster : Lance Armstrong's "It's Not About The Bike" fell into my lap just as I was making the transition between mountain biking to road cycling and I enjoyed it thoroughly.
I read the book listed above and found it "too soft" on the science end for me. I couldn't get past the first few chapters...there were many good techniques in the book, visualization of goals, learning about your psyc. and figuring out just what makes you tick...or is holding youback from suceeding...The writing seemed too easy. (Then again I am an engineer by trade...)
I would look harder into the general sports/success psyc for books. Just my .02.