The written is well, written, in a way that it will try to test you to the limits of your knowledge, so if done right, you will feel you failed, and failed horribly. Per the NREMT, everyone gets about 50% wrong and 50% right on their test.
I felt like I failed when I took mine 2 weeks ago. I was not a happy camper for the next day waiting on reults, but alas, I passed. Just know your material, and start with airway, and you'll be fine.
Theoretically I guess the written should be the harder of the two because aside from the oral stations, you just have to regurgitate the steps on the paper... but I myself freaked out more for the practical skills. For static and dynamic cardio-- You're already ACLS certifies, so you know you should be fine on them barring a stupid mistake (Like calling a 1st deg block a 2nd type II... no comment)
The oral stations seem to be where everyone freaks out about failing the most. Just walk through the call verbalizing EVERYTHING. Ask about the weather conditions. Ask about how the house is set up. Explain every little detail of a call (within the time limit) and you'll be fine.