Great terrain, back bowls
Weather can be very cold
I have been skiing at Lake Louise for many years. It has the best terrain in Banff National Park - more interesting and varied that Sunshine Village. Take the Summit Platter and ski the back bowls for the best snow and most challenging terrain. However, overall, Lake Louise tends to get less snow than Sunshine Village. Slopeside lodging is non-existent and nearby options are limited. If it is within your budget, the Chateau Lake Louise is one of the best hotels in the world and very romantic. The worst thing about Louise (and Sunshine) is the possibility of encountering very cold weather. Last week it was -34 C (-25 F) in the morning and they weren't even letting people on the lift. The previous day (high temperature -18 C, or 0 F), I got frost bite on a portion of my face. And this is in March!
When the weather is mild, its a great ski mountain. I wouldn't go there in January and probably not February.