There is no software without bugs. But there are bugs and BUGS. Second ones are annoying, well known and no one work on getting them fixed. Few examples:
FireFox/Iceweasel — many people use it, many people want to kill their developers. Why? It leaks memory, it eats memory, it can take 6GB of memory just because there is no more memory available in system. Problem exists in 2.0.x but also in 3.0 trunk version. No solution developed.
KMail — flagship of KDE PIM. It can fetch mail, send mail and do many other things with mails. And it can handle OpenPGP/GnuPG signed/encrypted ones. But a way how it handle them is horror. Whole UI freezes, no updates for several seconds just because someone decided to sign all his mails. Bug was submitted over 5 (FIVE) years ago, there was one major KDE release and many minor ones but bug is still present. No one even marked is as important.. No comments
I can live with first bug as for most of time I use Konqueror. But solving second one needs to wait until Mailody will get more usable so I will be able to switch to it. I lost faith that KDE PIM will get into more usable state then it is now.