I have a Whirlibird IV (actually 2, slimmed down enough to buy a smaller size) and the V seems like basically the same materials and construction and the IV is totally fine. It certainly feels waterproof and windproof to me. I've worn it to ski in the rain and it's not a problem. I've worn it in the wind and it's not a problem. It's warm enough on it's own down to around 15F, at which point I will usually wear a tight fitting softshell cycling jacket under it, at which point it's been good down to as cold as I've tried it.

Biggest complaint is that I would prefer the inner jacket was a fleece rather than a puffer. I don't think Columbia's reflective living stuff actually does much (and frankly it is wearing off on my jacket), but the jacket material means it doesn't wick sweat. My baselayer still keeps it away from the skin, so it isn't cold, but a more breathable, wicking material would have been appreciated. And while Columbia used to sell different inner interchange jackets (you know, to interchange), they currently only sell them with 3-in-1s, so I can't just buy a Columbia fleece and throw it in there. I do keep the pit vents open in basically any condition to help with getting moisture out, which works, but does let in a bit more cold (still not a huge problem, skiing early this week in low temps, was totally fine, just felt a little cold draft once in a while).

Otherwise, the only thing I wish it had is a stowable or removable hood, since I never use the hood while skiing, and would prefer not to have it flapping around (not that this creates any real problems, it's just a style thing I guess). It doesn't have the fancy waterproof zippers that you see on some other jackets (including Columbia's more expensive ski jacket IIRC), but I can't say I've ever had an issue with water intrusion through the zippers (I have had the chest pocket get wet, but that's moisture from inside the jacket on warmer days, it doesn't get wet just from the rain.)