I got this idea from problem 7 on http://www.logicmastersindia.com/mock10R1/SudokuMockTest10PBR2.pdf (password: DruhaCastMock10). My puzzle uses a slight modification to those rules (detailed below). I'd appreciate feedback on this puzzle:

Rules:

Standard Sudoku Constraint - Fill the squares with the digits 1-9 so that each digit appears once in each row, column, and 3x3 region.

Hidden Skyscraper Constraint - A grid square contains an arrow(s) if and only if the number in that square correctly indicates the number of skyscrapers visible in that direction. (This is the modification from the mock test: if there is no arrow in a particular direction in a particular square, then the number of skyscrapers visible in that direction from that square is NOT the number on the square.)