I've encountered some strange and non-obvious behavior when importing torrents.
One of the torrents which was updated on the server and I redownloaded it and tried to import. After data check ktirrent showed a window saying that I was missing all files except only two of them as I expected, after a quick look I found that root directory name in the torrent haschanged and it was not able to recognize old files. That is ok and nothing to blame ktorrent. I pressed "Cancel" and torrent went red saiyng about missing data. I then pressed start on the torrent, the dialog with missing files showed again, I selected "Chose new location" pointed to the new locationand after I pressed OK the torrent went to downloading state without checking data, and as this was a new torrent it had 0 downloaded although most of the data was there. Thta is not right. Also I should say that in the end everithing is ok, but the steps were not obvious and a bit confusing.
So my main concerns are that torrent import is weird, it doesn't show nice progress as in "Recheck data", it doesn't have any configurations, it blocks GUI and so on. And chosing new location should autostart checking.

I'm not sure it's related, but I have a number of torrents which have changed the location which they show in the torrent list. Opening the data directory fails (because the new location does not exist), but the data check works just find.

For instance, instead of being in /home/myuser/torrents/thetorrent/, the location which is shown in the torrent list becomes /thetorrent/. I have quite a few torrents which think that they're in the wrong location like that. But I also have quite a few which still have the right location, and I don't know under what circumstances ktorrent gets confused.