Pros: Meribel is at the heart of the world's largest skiing area
Cons: it can be a little crowded
Meribel is the central valley of the three valleys skiing area, which claims to be the largest in the world. I have visited all three valleys and I would recommend Meribel as the most versatile one.
I have been going to the valley for several years now, always staying in Meribel-Mottaret, the smaller resort at 1800m. The main resort at 1400m can get a bit too crowded and the snow on the lower pistes can be of lesser quality, despite the huge number of artificial snow canons. However, being a small resort, Mottaret does not have much to offer besides great skiing. There are just a couple of bars, one disco and a small cinema. The night life at the main resort is much more vibrant.
As far as skiing is concerned, Meribel is the most versatile of the three valleys with pistes ranging from very easy (green slopes) to very difficult (black slopes). The valley of Courchevel has the easier pistes, which might sound good for beginners. However, if you learn to ski at Courchevel, you might get in trouble when going to another resort. If you can ski in Meribel, you can ski anywhere. The third valley, with resorts like Les Menuires and Val Thorens, is the most difficult one, but there you have to deal with the horrific, concrete architecture of the resorts. Why this valley is referred to as 'La Vallee des Bellesvilles' is beyond me.In short, Meribel is great for both beginners and experts.
Besides charm and versatility, Meribel also has the advantage of being the middle valley, making it the ideal place to stay if you're looking to explore all three valleys. The downside of its central location is that pistes can get a bit crowded, especially during the French holidays.