Yes I did notice a little noise with it being mounted vertically but didn't have any option with my setup, although I did think that as far as cleaning goes it would make more sense to have it mounted horizontally. You could then shut off the valves and take the front plate off to clean without losing any fluid at all. The noise abated as I reduced the flow of the pump anyway.

The ports are quite clearly marked as inlet and outlet but I did find that if I connected them up this way it was much harder to clear the air from the unit. Maybe there again that could be down to mounting vertically. I then swapped the pipes around and the air was cleared much easier. It does mean that any debris is trapped on the front side of the filter now as opposed to behind it. In my opinion that is a good thing as it makes it visible.