Yes.
I'm a UA flyer and travel Chicago-Toronto a fair bit. I've been cheating on United and using Porter. What a positive change.
Using UA/AC - 60 minute train ride to ORD, deal with Pearson, $70 cab ride into Toronto - reverse.
Using Porter MDW-Toronto City airport. 20 minute train ride, half empty plane (usually), no one in line at Immigration in Toronto (usually), free shuttle bus to the city center. Returning, pretty much the same - Porter has a true departure lounge free to use by all complete with free snacks and coffee/soft drinks, no line at immigration at MDW (except when the plane from Mexico sneaks in front of us (aaargh), then another 20 minute train ride and I'm home. Using Porter I can be home in the time it typically takes me just to get out of ORD.
Porter rocks.