Not happy at all. Mark (the owner) came with a helper. The helper vaccumed the duct in ONE minute, and then started cleaning up. I saw very little lint came out. Mark told me it's done and he was about to issue a receipt. I stuck my hand through the vent and able to scrap some lint off the duct. Then Mark said 'oh yeah, we are not done yet.' (I think he was done already if i hadn't tested it out with my hand). He then went to his van and took out two small short bristol brush (shorter than a toilet bowl, like the ones you wash dishes with) and acted like he was doing something. I insisted that he use those longer ones, which he later did. But I think the proper way should be use the longer one first, losen the lint, and then vaccum. Too bad I didn't watch them closely.
I only cleaned this vent after 7 years and I was expecting a lot more lint coming out, extremely poor level of service.
My advice is for anyone hiring contractors, you must do some homework what's the invoved (youtube) and then watch them do it infront of you. They cut corners!