Not really sure myself. From my perspective they have about as much power as the Queen or the Governor General. In other words, very little to none. They are just figureheads for the most part, playing the role of MC at public functions. They can't authorize the expenditure of tax money, or the collection of tax money. They are not elected. There were senators appointed decades ago who are still holding their positions. As a result, the senate is not dominated by a particular party. If there are no empty seats in the senate, the current government may not appoint any new senators.

The Legislative Process: After a bill has been through a few rounds of debate by MPs in the House of Commons it is passed on to the Senate for a final review. If the Senate makes any changes, they send it right back to the MP level for acceptance or rejection. Essentially, they are like consultants on various issues. A bill won't be made law unless both the House of Commons and the Senate agree to it. It is undemocratic.

Some Canadians think that Senators should be elected. My opinion is that the Senate shouldn't exist at all. After all, we have a House of Commons, why do we need another? But that's just my opinion. Find me a governement anywhere in the world that is perfect.