I like this tool. I was testing it out when it was released, found it strange in the beginning (when you simply don’t get it), then I saw one tutorial from izzyvideo.com that explained very well the concept behind it and from that day I understood the often used sentence from the podcast FCPX-Grill by Chris Fenwick: “FCPX solves problems that you didn’t even know you had”
I use FCPX on very big projects to compare playouts, use markers on off- and on-line edits as a visual todo list (that is very easy to update over time), on shoots to prepare special footage or create animatics and I even used it to give a presentation (like a film centric keynote app).