Since this is not an open-source project but it is still massively used and since it has so many features it is perfectly normal for bugs to appear again and again the one after the other! The good thing is that there is this forum where comments are actually heard and taken into consideration. I personally like those new versions with bug-fixes. The only problem is when they come out too often because all people can't follow the version changes! We still have people scripting in mIRC 6.03...
Anyway, no open-source == 10 times more bugs but as long as old scripts keep working in newer versions and bug reports are being heard and taken into consideration everything is cool!
Note: I'm not suggesting giving away mIRC source code (although this would be a great idea for coders - a bad idea for Khaled perhaps) but I'm just explaining why it's normal to have so many bugs in such a big project! In any case why should bug-fixes be bad for anyone? Ok perhaps lots of people whine about new versions... However, I think everybody will agree there's no other way and it does make us happy..
After all mIRC IS becoming better... not worse!