Having been a huge fan of the movie version for years, my approach to the book was understandably loaded. I already had an image of what the characters would be like and how the plot would unfold. As I read, I kept referring back to the movie and comparing the two versions - sometimes favourably and sometimes not. Ultimately, however, I realized that the two are entirely different entities, having only some plot elements and names in common. 
 Overall, I found the characterizations of the movie to be more enjoyable, from a purely emotional stand-point. I don't think any film has ever captured the awkwardness of growing up quite so well as Adso's kitchen scene with the village girl! Sean Connery's William was the familiar figure of the innocent and slightly naive genius. And then there's Ron Pearlman's Salvatore - a character the book version can only be a poor foretelling of. 
 In the novel version, however, the characters didn't come through as much - perhaps because they were more realistic and didn't draw quite so much on stereotypes and archetypes. On an intellectual level, this worked just fine. On an emotional level, however, I just had too much trouble bonding with any of the characters for it to really work. That being said, I don't know how much of this is because of the movie version's taint. 
 The novel is long and slow (an intentional feature, if the appended essay is to be believed), but it is never tedious. The rythm is steady and only as slow as it needs to be. Whenever I would feel myself just starting to get bored, something would happen. Eco showed an incredible sense of pace in that sense - every scene is exactly as long as it needs to be. 
 All in all, it's a great novel. It is, however, very dense. I am glad that I waited until now to pick it up because I think that I would have been turned off by it had I tried any earlier. It's a wonderful novel to read for someone who has been studying Medieval history as a hobby for quite a while and wants a good illustration of the complexities of society/theology. 
 My recommendation would be to try reading it, but to put it down immediately if it seems to dense or boring. Try it again later. It would be a terrible shame to predispose yourself negatively to the experience simply because you tried to get into it too early.