The composite bow looks so badass. The rifle is best for firefights, but I think the bow is the best overall weapon hands down. The pistol is good for headshots, while the shotgun is nigh useless IMO.
And I loved Shantytown. There hasn't been a single area I haven't liked. The forest at night was definitely among my favorites though.
As for the sequel, I actually don't care about a better supporting cast except for perhaps a slightly more developed villain (although he's good if you get and read all the documents). I think this game would have been better if the only characters beside Lara were Roth, Whitman, and Sam I guess. The rest are nothing. I really only care about Lara, so keep the focus on her next game more solely.