Hi axelinux! My experience: K3B is a better burning program - it's available for Gnome although it was developed for KDE. I burned many CDs / DVDs and never will use brasero again, because I had troubles with it. But I don't know if it is available in Debian - you could search with a Software Manager. seeley
I've had trouble burning dvd iso's with Brasero as well. However, after I installed DeVeDe and Avidemux I discovered that burning iso's worked. Not sure why or which one did the trick as I installed them both before attempting another burn. Alternatively you might try Gnomebaker. Some people claim it works better than Brasero.