I am a native English speaker, and will be taking the IELTS on Dec. 4th. I'll let you guys know how it goes!!
I did a few practice tests, and, overall, they'd be quite easy for native English speakers. The only part where I was dumbfounded was a part in the Reading section which contained an incredibly badly drawn diagram; that worried me, though I doubt it'd really affect much of my final grade. The Listening part is quite simple, EXCEPT for the fact that you do have to hang on to what you hear while listening to new information; luckily, the questions are in order of what you hear. Like others have said, you CANNOT get distracted, because you'll only hear it once.
I also don't like the format of "do not write more than three words"....don't really see the point in that, other than testing to see that people can follow instructions.
Now the French test I'm not as confident about...

;D