It doesn't sound bad to me, actually I like it. But then, I make a lot of crappy songs myself, so my opinion might not count as much as others, XD. I like the drums and I think the rhythm guitar sounds great. Overall it has a great impending doom metal sound to it. It just seems a bit weak on the technical aspect in places, as you mentioned. But thanks for uploading, it has inspired me to finally put new strings on my guitar and attempt to make a heavy metal song of my own (is that possible in GarageBand? I'm gonna find out, I guess).

Cheers! :)