.PDF vs .Epub

Is anyone else having problems reading commercially produced ebooks on their ereader? I'm getting a bit irritated with buying a book then having to jump through all kinds of hoops to convert it to a readable copy. If I was buying from Amazon's Kindle Store, I'd expect the inconvenience - more fool me for buying a Sony, eh? - but when I buy from ARE or Smashwords or direct from the publisher and opt for an .epub file and it's STILL unreadably small and won't respond to resizing I get peeved.

Yes, I'm probably doing something wrong, but I can't figure out what.

This week has been knackering at work and since himself went back to school he's been chatting to himself all night. Not a good combination. But I managed to settle down last night and wrote over 1000 words spread between my spies and my pirates [who I decided DON'T need to boink after all if they don't feel like it. I know that the market demands a certain level of squelchiness, but I don't and I don't have to try and sell it if I don't want to]. Most satisfying.

Also I perpetrated fanfic, but I can give it up anytime I like. :D