Atmosphere is better at dinner. As others have mentioned, there's the Beast and it's more elegant. As for the food, my wife and I greatly prefer the lunch over the dinner, which of course is personal preference. We typically do the dining plan, so price doesn't matter, but the only thing we both thoroughly liked for dinner is the steak, but it's just as good as most other Disney restaurant's steaks.
This past trip, we booked both lunch and dinner. We put the lunch on our dining plan, but dinner we just went to enjoy the dinner atmosphere and both got soups and a dessert and paid out of pocket. However, our waiter was noticeably irritated once she realized that we weren't getting anything other than a soup and dessert, which made us feel a little weird (honestly dont think she said more than 5 words to us the rest of the dinner, when she was extremely talkative before
). We've decided not to do that anymore, however, as we did feel sort of bad for taking up a reservation spot (they sat us two people at a 6 person round table..?), and we dont want to be an annoyance to the waiter (I promise we do tip very well though!
)
Sorry for the off the topic ramble, but as for us (Mid-may trips and late Jan/Feb trip), we never have an issue getting a reservation at the 180 day mark. Usually have plenty of options....though, I do believe we booked the dinner at BOG at the airport before we flew down, so if you don't get one initially, as always, **keep checking**, because more than likely, one will pop up at some point.