I have seen both of them now and for the playable pair, I think they are alright, although I would have liked both to return earlier, preferably Act 1, it would just give more time to try them out. By the time you reach Act 3 you likely have a preferred set of characters.
The two unplayable ones, yeah I agree. Now I do not know what their canon ending is, but I would assume that most players probably took a somewhat good route. If you have done that with those two characters then you will likely be disappointed, as it will just be a step back, just like having them as companions did not matter. Even when embracing the evil path you could have just replaced them both as Mr. Evil Guy and beyond the initial "that is the dude from the other game!", you would not have missed much.
