I am not a particular huge fan of the original 300, but I do like it for what it is. I'm afraid this is not up to par quality wise.
I thought this was to be a sequel, but I was wrong, it's more in parallel of the original, with a bit of prequel and sequel around.
I did appreciate seeing some of the original cast back, it was definitely nice, even though the movie is not about them (too bad!).
This movie follows the previous one with its central characters, and unfortunately the comparison isn't good for it, and this is exactly my biggest issue.
* Leonidas is replaced by Themistokles:
I have no problem with Stapleton, he seems a great actor, but unfortunately his character is far less interesting. He's pretty much a good guy that cares a lot for everyone with little humor, I found it somewhat boring to watch compared to our previous lead. I understand that it represents the difference between the Athenians and the Spartans, but it doesn't really work out for me, maybe it would have with a better co-lead.
* Xerxes is replaced by Artemisia:
Now this really did not work. Xerxes was awesome (in limited quantity of course) whereas Artemisia not quite. There was something about her makeup that made me wonder if she was on meth or a goth or something else that did not belong... Forgetting that, her build is not of a warrior, there is no way for her to wield a sword and a shield all day like this. Why are all the guys huge but her, the best warrior of Persia, so tiny? and yet she's the only one wielding not one sword, but 2! (yes yes I understand skills... still I'd expect more a build like Ferris Hellig, especially for a 300 main character!). Some of her scenes were fine, even if not super interesting, but I felt some of her last speeches lacked feelings).
* Dillos was replaced by Aeskylos:
It's not that Dillos is such an awesome character in 300, but he's good enough in most of his scenes and great in his last ones. I never felt anything good about Aeskylos, this time it's probably both the character and the actor. It's like they needed Themistokles to have some discussions so they sort of forced this guy in, but he serves no real purpose.
* The father and son are replaced by... another father and son! The evolution of their relationship is interestingly opposite, as again one would expect between Spartans and Athenians and that was good, but the characters are not that interesting and the boy that needs to prove his worth to his father is not that fun that we needed it. The dad is fine, I think he should have taken over Aeskylos's role and have more screen time.
* The multiple Persian armies are replaced by the Persian Navy: That too was fairly boring in comparison. In the first one you never really know what will be coming next, but here it's always the same... Well it is less insulting to Persians though since it has no demons/monsters this time :)
The main characters, which is what the movie is really about, are unfortunately fairly boring. The sex scene has no purpose but itself... I could understand one of the 2 characters taking part in it, but definitely not the other A few things seem to contradict between the 2 movies as well, but nothing too major. The first battle had so much blood, they even splashed it on the camera, it was annoying.
All in all, nothing to remember.