Gratuitous plug for my YouTube "Let's Play" playlist.
All the videos I've compiled and uploaded to YouTube have been made using Kdenlive. I don't labor under the notion that it's perfect, but I found it much better and more accessible that anything else I tried.
Kdenlive's most annoying bug at the moment is that the sound in the final compiled video will sometimes drift, i.e. in an hour-long video, the sound will start off in sync with the video but, by the time you get to the end, it's as much as 1.5 seconds off. This drift does not appear when playing back in the editor timeline; only in the final compiled video. I have not been able to reliably reproduce this issue for the developers, nor do I have a notion of what triggers it. Once it appears in a project, it's there and you can't get rid of it. It's possible it's an issue with MLT (the library on which Kdenlive is built) but, again, I haven't isolated the issue.
Other than that, it's worked very well for me. Even on those occasions when it has crashed, it has never destroyed my work; just re-launch and pick up from where you left off.
If something better came along, I would jump to it without much thought. But I haven't found it yet. I'll give 'pitivi' another look, but it looks as if installing it into my generic Debian system will be a pain (v0.92 is only available in the 'experimental' repository).