Orientation of Particle Instanced Objects
The local Y-axis of the instanced object is mapped to the X-axis of the particle used for the instancing:
1) Before Object Instancing
The particle is displayed as a "Coordinate Cross" with the X-Axis in red pointing upwards. The "Coordinate Cross" at Suzanne shows her "Local Coordinate System" orientation.
2) After Object Instancing
Suzanne is looking downwards since her "Local Positive Y-Axis" is pointing into the direction of the "Positive Y-Axis" of the particle used for instancing her. Only the rotation isn't predictable and has to be adjusted to your needs.