I actually haven't had many moments where people don't comprehend that either The Hobbit came before Lord of the Rings or that they're from the same author, thus similar.
However, I'm really on the fence about seeing it. I honestly love The Hobbit, but from what I've heard, I'm a bit unsure about how it's going to work. My brother and I were actually discussing this a few days ago.
First off, I don't know exactly how they're able to split it into two movies. I mean, it's really not that long. I certainly don't see it being so long that it can't fit into a two hour, maybe three hour movie. Most movies are now floating around two hours anyways, if not longer.
Next, where are these Lord of the Rings characters coming from? When I first heard the names of who was returning for The Hobbit, I just couldn't wrap my head around it. Now, I know there's not as many coming back, but still, I just don't see how they fit in. Legolas, maybe. They're in Mirkwood, but it would be a cameo at most. Frodo, I don't see at all, as Bilbo was 78 when Frodo was born (so, logically, Frodo doesn't even exist during the Hobbit), unless it's during an introductory, "let me tell you a tale" thing.
Then, Dol Guldur. We just don't see how they're going to be able to pull this off. To both my brother's and my knowledge, there's just not a whole lot of information out there from Tolkien about what happened there, unless there is more information in the History of Middle-earth series. The most we could come up with was a slight flashback from Gandalf (similar to how you learn what happened at Isengard when Frodo wakes in Rivendell).
I'm interested though in seeing Beorn for sure. And the three trolls in the Trollshaws. It's still one of my favorite parts in the book. And the Battle of Five Armies.