I recently used Epractize Lab for baselining my score just 1 week before my Exam. The question is not upto the mark. They are very short in length & many of then are too simple & repetitive. I suppose free Mocks on Javabeat & about.com are much better
Actual questions on Exam are too lengthy. In my case I even didn't left time to review any of my marked questions. Better to concentrate on lengthy question & also make a habit to be in test taking mode even while attempting free mocks. So be wary.