I have used them several times. They've always been top flight. I always received the tickets in less than a week.
It is important to do your homework prior to buying the tickets though. Find the web site with the best price (including shipping) for the tickets you want. Then check Maple Leaf's price. If the other place is lower than ML, just email them with the details and URL and they will sell you the tickets for $1 less than the other site and include shipping. I have had them price match several times with no problems at all.