Tobit's hymn of praise would not seem out of place in the Psalms or as a poetic passage in the prophets. It just falls sort of those passages poetically, though. The themes of the book--justice and mercy from God--are again stated. Verse 6 prety much sums it all up. There is a lot of praise for Jerusalem for someone who was part of the breakaway northern kingdom of Israel, though.
The last chapter wraps everything up. Tobit dies, but not before he warns his son to flee Nineveh due to the dire prophesies of Nahum. Tobit does a bit of end-time prophesying of his own, looking to the day when Jews and Gentiles together worship the true God. Tobias lives to see the fall of Nineveh and praises God for it. Both he and his dad live to within spitting distance of 120, the Biblical limit to human life.
All in all a pleasant and pious fiction.