I cleared the Websphere Portal test # 399 with 60% . I studied for around 12-14 hours in around 2 days. The test is tougher than the Prometric mock exams.
Important Topics 1) JSR-168 specs ( Study very well) 2) JSR-168 API ( Go through all classes ) 3) RAD 6.0 help ( You can download the Help zip file from IBM site). Focus on the topics mentioned in the objectives. Important ones are: 1) Installation - supported OS 2) Portal Development using RAD 3) Debugging & Remote debugging 4)Struts Portlets 5) Co-operative Portlets