It's fairly responsive to your needs. It will pick up on an email threads importance (as in a mailing list) fairly quickly. From what I gather (not knowing any

It's fairly responsive to your needs. It will pick up on an email threads importance (as in a mailing list) fairly quickly. From what I gather (not knowing anything official about Priority inbox), it seems to take into account how long you spend looking at an email (either thread or from an author). Email threads that I zip through never get tagged as important, whereas some threads that I've spend time looking at it will tell me that it's important from then on (and pick out other emails that are somewhat similar in content) It also responds fairly quickly to changing preferences. I've had threads, regular email updates that have been tagged as important (either by me or by silicon) and I've had a change of heart and untagged it, and it won't mark it as important, and I'll notice a dropoff in similar topics being tagged as important. It's nice, as I used to get a ding for every email I received, and I felt compelled to at least _look_ at it. I've since set it to ding only when something tagged as important pops in (only up to 5 times a day) and I'll only check all my other mail maybe once a day. If that.