Pros
Pay is fair and benefits are above average. There are opportunties to work with varied projects since it is a consulting firm. That helps it not be the same thing one quarter to the next--unless you're on a really big project.
Cons
It's not like you're working for one company. Stantec grew by acquisition and it shows. It's more like a network of affiliate companies or one big joint venture that happens to use the same financial system, IT support, and policies/procedures. Many offices hold work close to them and don't spread the opportunties. This is especially true if they specialize in a particular engineering consulting market. It is a public company and the shareholder is king--like any other public company. I came on through an acquired company. The culture we had went through the meat grinder.