Yes, the weaknesses of this movie are numerous. The acting is, for the most part, horribly wooden, particularly with the lesser supporting characters. The real-world history is way off (among other flaws already pointed out in other reviews, "Journey to the West" is, according to what I've read at least, closer to 400 years old than 500, and the official objection to the manuscript was its nontraditional form rather than its content). Some of the characters, particularly four of the Five Traditional Masters, are way underdeveloped. Portraying Confucius as a self-serving sycophant is just *wrong.*
If you're already familiar with the original story of "Journey to the West" and can't bear to see it butchered -- which is exactly what happens here -- then follow the one-star ratings given here and avoid this movie like the plague.
For anyone else, this is a fun piece of work. It was hardly Emmy-worthy in any category (with the possible exception of Bai Ling's impassioned performance as the Goddess of Mercy) and has numerous plot holes not worthy of David Huang, but the story travels on well with only a couple of relatively minor diversions (well, I guess NBC wanted to make sure they had a good two-part miniseries), one can really care about those characters that do receive proper development, and can wonder and worry about the story's outcome.