Thanks a lot for your appreciation!!! Here is my experience with SCJP I took 2 months to prepare for the exam, read K&B book twice, solved the self test thrice. I tried to solve all free mock exams as mentioned in the SCJP FAQ. K&B mock exams are really very difficult but it will definitely help you to score good marks in actual exam. Real exam was very easy compare to K&B mock exam, The only problem I faced during the exam was that i could not review D&D questions. So in my opinion, give full time to D&D question as there wont be any review.
Apart from threading and generics, there were many questions on inheritance, polymorphism, exception handling etc.
Thanks Sandeep for sharing your exp with us. I am plannin to go for SCJP1.5 upgrade exam. Can anyone clarify me how upgrade exam will be different from main exam. Is there any study material for exam preparation?