Writing two different books let alone two completely different mythologies(Greek & Roman to Egyptian) almost at the same time is quite a hassle.
Mr. Riordan knows how to incorporate facts into a good story and also makes it quite interesting. Shifting characters from Carter (the scared older brother who needs to step up and knows almost every Egyptian mythology)to Sadie(the very sarcastic British girl) for me is a good change. It gives me both sides of the story from each of the characters unique perspective.
Though there is a pattern: From planning something ---> applying the plan ---> Something goes wrong (of course they're the Kanes, something always goes wrong) ---> to someone helping them fight or saving them (which I can understand seeing they are just novices)
Although the pattern is there (and some predictable plot twists), there are some unpredictable situations which can either be baffling or simply quite entertaining.
The Kane chronicles for me is a great book. This is a MUST read for mythology lovers such as myself.