Well we are talking about the actual pace of the dialogue and not the content and so I will express my opinion:
I think it depends what type of person you are. I mean when I saw Vol. 2, I did notice that they talked slowly but it didn’t put me off one bit. I don’t take QT’s dialogue for granted, and so I listen and pay attention to every word, no matter how fast or slow it is delivered. Vol. 2 was more of a character driven movie where we learn a lot about the characters, and in keeping with this ‘real’ feel, QT made the dialogue go at a pace it would be spoken at in real life. Also, the ‘western’ aspect, as Johny mentioned has also got something to do with it. I am a (spaghetti) western fan, and I noticed how the content of the dialogue and the pacing of the dialogue as well as how the dialogue is delivered is very similar to how it was done in the westerns. Budd especially talks just like a cowboy, and Uma too at times - "I guess that makes him a liar now, don’t it?"
I did think however, upon watching Vol. 2 for the first time (I didn’t like it then by the way) that the dialogue dragged on quite a bit during the end chapter. But now I am used to it. Slow paced dialogue isn’t normally commonplace within a Tarantino movie (I often find myself rewinding scenes because the person I am watching a QT film with didn’t quite get what was said, and therefore missed a piece of briliance!). Most of his characters talk at a normal or fast speed, Samuel L Jackson’s characters especially. You will find people who don’t have much patience and want all the talking to end so that the guns can come out and the explosions can happen.
But the ‘slow talk’ in Vol. 2 contributed to the coolness of the characters in my opinion. I mean how cool is David Carradine in this film?