I love it with the quoted material being my only complaint. I find myselft having to move the mouse pointer the the extreme left of my screen to prevent this. It’d be nice if it only popped up on hovering over the thread title.
Other than that, it’s great.
Another vote for “love it.” I think the duration as it is now is just about right.
I love it, for all the reasons given – but esp. to prevent those “oh phooey, I read this already” clicks.
I find it helpful. And it sticks around long enough for me to read it, so that’s fine by me.
Maybe it goes away quicker with IE? I certainly have never seen it linger, but it’s often too short.
I like the thread hint myself… I think it’s purpose is somewhat defeated by use of descriptive thread titles but it’s nice to be able to see how a thread starts off. For example, I hate reading through the right vs. left mudslinging fests in GD but I like threads about politics. The preview usually lets me know if it’s a real discussion or just more “my candidate/party/belief is better than yours” tripe. So it’s a useful feature as far as I’m concerned and I find myself wishing other message boards that I like used it as well.
I really like this feature and would miss it terribly if it went away for some reason.
I’ll agree with what Servo says, though: that it’s slightly annoying that the whole thread area is popup sensitive. I’ve had to adjust my mouse-wheeling technique so I stay way off to the left, in the narrow margin between the window’s edge and the envelope graphics on the forum page, in order to prevent text-box flashes when I don’t want them. I’m almost completely used to the adjustment, now, so that minor annoyance is fading away.
Big thumbs up from me. I wish all boards had this behavior. I especially miss it when I’m at the TiVo Community board, which doesn’t suggest or enforce a policy of descriptive thread titles, so half of the discussions look the same from the listing.
I find it really helpful. But the fact that it doesn’t always work can be bit annoying.
At work, where I use IE, it annoys the hell out of me. At home, where I use Opera, I like it immensely. It is a pop-up on IE, but at home it is only on the status bar.
I love it too, especially for the reason above.
Nope, but then I’m a very fast reader.
I’m the opposite of the OP. At first I didn’t like it, but now I’ve grown to love it and I miss it when I am viewing other boards that don’t have this feature. I find it really helpful for all of the reasons that have already been said.
I love it, especially when the board’s running slow.
Now, on other message boards, I find myself with the cursor poised over a thread title, waiting for the little box to appear, but it never does. Sigh.
A real definitive answer. 
[sup]And they say Kerry flip-flops.[/sup]
I love it.
I hate that it’s only one line on my Mac, though. On the PC at work it’s a big box.
I like it, but without justification.