I nearly got put off reading these by the literary snobs on Amazon, but I decided I needed to see what all the fuss was about for myself. Most of the rubbish reviews seem to come from people who read half the first book, decide it is rubbish and don't bother with the rest.
This is where they make the mistake. You need to read all three and follow the story to it's conclusion before you can really decide. I haven't read or seen anything Twilight so didn't have the comparison to draw on but I think that helped me appreciate the trilogy on its own merits.
Admittedly, it is never going to sit alongside what previous generations have decided are literary classics, but it would be out of place there anyway. However, in the right frame of mind and with the patience to see it through to the end is a more than worthwhile investment of your time, if you like that sort of stuff anyway. I have read some utterly rubbish erotica in my time, but this is definitely at the better end of the genre. I don't really get on with visual adult material because movies have ridiculously ropey plot lines and it leaves nothing to the imagination. This however, has a pretty solid plot line, that gets nicely tied up by the end (pardon the pun), and is an engaging read, if you can make it past the first few chapters.