Good guide. Just wanted to check over the method for completing it with the four different owls. Picked my game up for £15 less than a week it has been out. Notice some retailers here in the UK are only stocking PS3 version, DS or Wii versions. At the moment, Amazon, ShopTo don't currently sell the Xbox 360 version.
For those on their next playthroughs, I would advise not skipping past too many enemies at the start, since you need to unlock the barge attack from so many defeats. I actually made it to the level where you are introduced to the barge attack but was unable to perform it, as I was 3 away from unlocking it. Since, only an armored enemy was on-screen, I had to quit out and play a bonus mission, get those extra kills and then have to start that particular mission again.