I recently has the chance to ride both the ION LRT in K-W and the Züm bus in Brampton. It was day and night.
The Züm articulated bus was pretty quick, especially in the late evening when it really... zoomed... but it was loud as heck, both from engine noise and from what sounded like hundreds of loose screws only barely keeping the thing together. Every bump on the road made a racket. The bus kneeling was loud, as were the doors. The whole experience was uncomfortable at best.
The LRT was luxury by comparison. The ride was completely smooth with the exception of running over switches, which had a muted rumble. It was fast too, with priority signalling that made it feel like first-class traffic. The trip I took was faster than it would've been by car.
If the HuLRT takes its lessons from ION, it can be amazing. So many people in this thread criticize it, I think, because their idea of light rail is based on the Toronto streetcars. That's not what a proper LRT is. Seriously, ride the ION to get a real sense of what we can accomplish with these kinds of systems in the GTA.