I don't know a huge amount about Bobby V at this point, but most of what I hear about him sounds positive. Regarding the bullpen, I'm fairly ok with it at the moment. Losing Papelbon sucks, but we have added an All-Star closer to replace him at a fraction of the price, and we also get younger. Speaking of youth, I like the addition of Melancon as well. He, Bailey and Bard give us some really nice young pitching talent. If Aceves doesn't start, he'll be a nice addition to the pen as well.
The main worry that I have at the moment though is regarding the starting rotation. I'm happy having Lester, Beckett and Buchholz, but it drops off after that. As I said above, I think Bard is a really good young talent, but "young" is the key word there. I'm confident that he can develop into a quality starter, but we have no idea how he will go THIS SEASON while he learns the role. Matsuzaka isn't a terrible pitcher, but he's questionable with his health. Lackey can be ok, but I'd rather have enough depth above him that he can be used more as an insurance policy.
Outside of pitching though, I wouldn't mind adding a R/H hitter to the OF. I like Sweeney and his defensive game, and (apart from last year) he seems to hit for a good average, but adding a righty, especially with some more power than Sweeney has, would help to mix things up a bit. Kalish sounds like a good young talent to me as well, but he doesn't seem to have a huge amount of power in his swing either. I'm also not overly happy with the SS situation at the moment. Scutaro doesn't completely suck, but he is certainly a weak link in this team in my opinion. I'd love to see Iglesias get a real chance. He'd add some more youth to the team, and is great defensively. The main concern with him is offensively, but with the rest of the hitters in the Sox lineup, I think we can afford to play a defensive-minded guy like Iglesias and let his offensive game come naturally.