One thing i have come to is that complex tasks run on a blown up version of how single checks work.
That is, a skill check works by you rolling your dice pool and comparing it to a success ladder, with 4 steps and a potential to crit. Most checks get mixed results early on, with full success more likely as you level for checks you are well trained for.
A complex task has 2,4,6, or 8, checks. You compare number of successful checks to the complexity, and determine if it is a total fail, fail with opportunity, mixed success, or total success.