BlueJ is a programming environment that has been used to teach object-oriented introductory programming since 1999 in two consecutive first year units at Monash University. An earlier evaluation of its effectiveness in helping students to learn OO programming in the first unit was inconclusive, although most students who participated in the study believed that it did help them to learn Java. It was hoped at that time that students would show positive effects of using BlueJ more in the second unit than in the first. This paper reports on a later evaluation study, when the BlueJ environment had become more stable and easier to install. It examines the reactions and results of students in the second of the two units. It also introduces a set of criteria for evaluating environments designed for novice programmers.