In reply to frisian:
I also have the Vidda Pros. I've found doing a Nikwax waterproofing wash and waxing helps the water resistance. As others have said they are not actually waterproof so I'd recommend taking waterproof overtrousers with you too in case it's starts properly chucking it down.
That said, I have found they are quite heavy. I typically only use them for camping/shorter walks/outdoors activities - I've not tried a strenuous walk due to their bulk. If I was planning climbing significant hills I'd probably opt for something lighter - though I might just be a weakling.
Congrats on the gift, they are great trousers.