The best part about Orion is the graduated difficulty of the problems for each topic. You essentially go from problems where you simply apply the core material (division, subject-verb agreement, etc) through problems where you see how the testmaker can obscure or make the problem difficult.
Additionally, I've seen how Veritas is improving the program even during my 2 months with them. They've also been very responsive when I've had questions though the in app chat. Overall very helpful.
