Kdenlive crashes on me often. It reminds me of the bad old days with Windows 98SE and Adobe Photoshop. Save often, reboot often.
Kdenlive does get the job done, though. I launched a TV series last week on local cable (Boise, Idaho USA) + the web: http://www.tvcycle.com/
That show is all digital, with the video being pulled in from SD cards. Most of the show is three shots, consisting of a main shot and two picture-in-picture shots on the right side. Kdenlive does the composites nicely, but when I load up a saved project, it forgets the track assignments for composites and I have to assign them again! That's probably the second most annoying part of the video process for me. With my Qwest DSL connection, sending 15 minutes of 1080p (30fps) to YouTube takes about 6 hours. That's the biggest annoyance, and more hardware or software won't fix that. They have faster accounts, but I just upload overnight instead