I felt pretty much the same as you. I'm glad I didn't pay to go see it. Though, different from you, I felt the second one was lacking just as much as the third one. The first Transporter is the only one I would recommend to anyone.
I found myself not paying attention to Transporter 3, as it lacked depth and material worth keeping an audiences attention.
"Cu è surdu, orbu e taci, campa cent'anni 'mpaci."