The first stories started off really well. They explored some great ideas, particularly around science. There were some excellent twists in each of the stories, including the idea that apes don't kill apes, but humans will kill almost anything.
The later issues didn't seem quite as satisfying. They felt somehow less interesting and harder to finish.
The flood was super interesting and is somewhat reminiscent of the Batman: Cataclysm story line. It could have been better, if there was more attention on the actual event. This is already a post-apocalyptic world, so it would have been interesting to explore that.
A few problems with this series.
1. The coloring made it difficult to differentiate the characters. Most of the ape/gorilla/chimp faces look almost exactly alike. They even dress alike. At times, I had to stop and study the panel to figure out what was actually happening.
2. The storytelling seemed rushed and some of the action felt forced. It should have been paced a little slower to explore the ideas. If we're reading a Plant of the Apes story, it means we're interested in this world. There were so many opportunities to have the characters interact with the environment and show us this world, but it all seemed like a backdrop. Slow down, let's appreciate this world in ways that they could not do in the movies.
3. The art was great. It just seemed like they could have adjusted the wardrobes and other visual elements to make it easier to differentiate the main and side characters. One of the main characters had an eye patch, so it was easy to latch onto him, but some of the others -- including the humans -- were hard to follow.
Overall it is worth reading, if you like the Planet of the Apes. It is still one of the best Planet of the Apes comic series ever published.