I do ext at the moment, and in fact, my trial exam is tomorrow. I hate it.
Seriously, don't do it unless you are really good at english and enjoy reading poetry and shit.
I think the syllabus is changing for you guys, but the stuff we are doing is irrelevant and pretty boring.
Personally though, I don't find the essay component of the subject very hard because if you know your stuff, then it's really easy to write an essay on it. However, I am really crap at the creative section and that's where everything goes downhill for me.
My teacher told me in Year 10 that I would do really well in ext. and that creative writing etc wasn't a bug part of the course. He lied - the HSC has two sections, one essay, and one creative writing, worth equal marks.
So the point to my rambling on, not to dissuade you from choosing it, but to warn you. I wasn't very committed and now I am paying the price. Instead of bludging and getting in trouble for talking too much in class, I should have paid attention. If you're willing to do that, then choose it.
Overall, if you are good at english, it's easy to get good marks (most of the time).