Go for the Snow and the Terrain
Not that big and rubbish nightlife. Mary Jane bad for boarders
You can read lots of reviews on this site which extol the virtues of Winter Park. It does have great terrain and some excellent snow conditions. However, if you've never skiied in Colorado before you may wish to take the following into account.
Coming from Europe you'll notice that this is not a big ski area. Sure, you can ski anywhere within the boundaries but it's nowhere near the size of some French, Austrian or Italian ski areas. Like everywhere in Colorado, as far as I am aware, this is a completely self contained ski area, so you spend a lot of time going from top to bottom. The other thing you'll notice is that about a third of the ski area is called Mary Jane and is almost all moguls. If you're a masochist then this may be fun for you. The locals love it but I just enjoyed winding them up by saying it should be flattened.
Having said all that you can still get a week's worth of entertainment out of Winter Park, particularly if you like off-piste and tree skiing.
Nightlife - I'm not sure how anyone could give Winter Park 5 stars in this category as it's terrible. Firstly, you have to realise that most American skiers are either only there for the day, this being the closest resort to Denver, and go home when the lifts shut. Secondly, if they're on vacation they are probably serious skiers or on a church outing. This means they eat dinner a 5pm (what's that all about, and why is the main course an entree!), and go to bed at 7pm. So the only people up for a laugh, after the lifts shut, are the workers, who are mostly South American, and the few Brits who go there. The bars are ok, but not great, and if you're expecting European apres, you'll be disappointed.
If you're a serious skier then Winter Park is a great place to go. Just don't expect the complete European experience.