Pros: Great ambiance, awe inspiring scenery, lots of long runs and good mountain huts and restaurants.
Cons: Still quite expensive, not great lift system and little challenging terrain.
I stayed in Wengen during March 2008. The snow was reasonable, though not great.
The village is a pretty, traffic-free area which can only be reached by cog-railway from Lauterbrunnen. Development has been limited and well controlled - whilst this does mean that the slopes don't get over-crowded, and the village has kept its charm, it does also mean that supply and demand lead to fairly high prices.
There is a cable car and cog-railway to get you up the mountain from the village. Whilst the cog-railway is slow, it does provide an option which is almost never closed due to wind. I say almost never as I've been on it when it's been turned around due to horrific winds at Kleine Scheidegg (the primary mountain that Wengen's slopes are on.
Rostizzas for lunch is a good bet at the highest railway station in Europe on Kleine Scheidegg. Essentially, it is a huge rosti with tons of Swiss cheese on top, then covered in the toppings of your choice. You can smell the place for miles with the strong smell of tasty Swiss cheeses.
There are good options for skiing down to and around Grindelwald, and across Lauterbrunnen on the Murren slopes (which play host to the James Bond mountain restaurant from On Her Majesty's Secret Service).
Generally this is a cruisers paradise, with plenty of wide intermediate slopes to make your way from mountain hut to mountain hut down, stopping each time for lovely hot chocolates (with a shot of whisky or brandy, of course...)
In conclusion, it is a lovely resort which must be done once in a lifetime. It's just not a great ski area - good, but not great.