What this movie has achieved so far after 2 installments is that it has made Greek mythology very palatable to the young ones because of the interesting adaptation it has done as far as setting and characters are concerned. They have transformed ancient Greek into the modern era and made the demi-gods like they have just come out of puberty.
This has been the big thrust of the whole series of the source material of this movie by Rick Riordan in an attempt to come up with another hit like Harry Potter. And this is clearly felt watching this movie except that while Harry Potter is completely a product of Ms. Rowling's imagination, this whole Percy Jackson series is richly based on Greek mythology which makes it quite interesting as a study material.
Watching this movie is like jumping from one adventure to the other and the rhythm by which this story runs is just enough for the general patronage to appreciate. At best it is quite entertaining but it is little boring to a point. Comparing it The Lightning Thief, this sequel lacks a clear sense of mystery because everything is just presented like it was a night time story being told by your grandmother to put you to sleep.