Pros: perfect location, amazing and helpful staff, very good breakfast with excellent swiss cheese. We stayed for New Year's and the dinner at the hotel was very good and at a more reasonable price than most other restaurants. We also had a raclette dinner there and it was delicious.

Cons/ Bedroom: we stayed at the Lac Lodge, just opposite the lake from where the hotel is. The bedroom was huge, actually like a youth hostel bedroom, with 8 beds! It was clean, with enough storage for the 4 of us and more. The bedroom was cleaned everyday and the guy at the reception was also very friendly. The ONLY problem for us is that whenever there were people in the bedroom next door we could hear them. If they wanted to talk until 02.00 am, we could almost participate in their conversation. Since we were there for skiing and had to get up early my husband had to knock twice on their door ( two different groups at each time ) and ask them to speak lower. Usually we waited until after 11pm before we did that. Because we have kids there was no other way, since they also had to sleep . If you can sleep like a rock, go for it. But if you are a light sleeper or is just usually annoyed by noise, it's better to look for a rental chalet. About the bedrooms at the main hotel I cannot say anything.

We loved our stay at Hotel Du Lac! I wish I was better remembering names, but we were greeted by a charming lady when we checked in. She told us a bit about the place and mentioned that the owner brewed their beer and roasted their coffee. I mentioned that I home brewed, and she said "I shall tell my manager." Sure enough, when we came down later that evening, he was there, greeted me like an old friend and of course we talked beer.
The beer they brew is great! We also attended an event in Crans and it was his beer that was served. The weather called for rain and the peaks were in the clouds so we asked about things to do. We were told the weather would be better in the valley and he suggested a tour in Sion. Because we had our Swiss Travel Pass, getting there was no problem and the museum that we toured was free. His recommendation was perfect for us!
Our room was tight by American standards, but comfortable. We had a mountain view from our balcony that was awesome! The location was perfect with an easy walk to either Crans or Montana. Since we were using our Swiss Travel Pass, we came to town via the Funi from Sierre. We chose to walk to the hotel,but there is free bus service in the area if you choose. Breakfast was typical for the region with great coffee! We did not eat dinner there but based upon the cost of eating in town, we most certainly will next time.
Bottom line... The staff is great, the location is perfect and we will most certainly stay there again should we return to the area.

but there are many other pros and no cons that I could notice.
The location is great, central, great view on both sides if the hotel and less then 10 minutes walk to the "funiculaire" that gets you to the skiing range.
The rooms are clean and comfie.
The restaurant is a great bang for the bucks, fixed menu but very very good food.
Finally, let me repeat myself, the staff is a gem: kind, always helpful not just at your request but on their own initiative.
Were I to get back to Crans-Montana, I would look for a room at hotel du lac.