I've recently started watching them.
300: Rise of an Empire, total piece of garbage. And this is coming from someone who liked the original 300. (Slight spoilers in my small review)
-The two main characters in this movie, Thermistocles and Artemesia (I had to look up their names(BTW, Artemesia = butterface)) are forgettable. They don't have any personality like Leonidas or Xerxes.
-No epic quotes like "This is SPARTAA!!!", "Tonight we dine in Hell!" etc, etc, but crap like "I'll attack the Greeks with my entire navy" ( wow).
-Predictable "Boss-fight"
-Boring father-son subplot
-Too much (bad) CGI
-Fight scenes were just boring in general. Thermistocles does a 30-Persian killstreak. Overall it felt like you're watching someone play a bad hack&slash video-game.
-Bad acting, boring storyline (it doesn't feel like anything is at stake).