I have to say that the magnetic timeline's "primary storyline/connected storyline" paradigm just does not work for me yet. The concept is this: think of a documentary. The interviews are your "primary storyline," and the music, titles, and B-roll are your "connected storylines."
In theory this is very cool, because a particular piece of B-roll is "connected" to a particular piece of interview in a particular place, and you can reorganize the interviews and the associated B-roll comes with them.
In practice it's really annoying. It assumes that you always have a block of footage that starts and ends with a cut-in video and audio simultaneously, which I actually almost never do.
The magnetic timeline also irritates me because I'm a strong proponent of track discipline. If I put something on V2, it's there for a reason. But in the magnetic timeline, items on subordinate tracks just jump up and down all over the place. Your music might be towards the top here and towards the bottom there. I suspect that in a complicated project, it will become impossible to find a given element.
Something I despise: the loss of Reconnect Media. Not having that on Avid was one of the worst things about it, and losing it on FCP hurts. A file suddenly went offline for no reason -- I hadn't moved it -- and I was just hosed. That sucks.
I tend to agree, and have returned my FCP X because of it. Track Discipline is the biggest thing ever for an editor, and without it, I can’t edit!