I'm also active on another forum where there are plenty of topics with issues/bugs people are running into.
Did you pay for the software, did you contribute to the software? If the answer is no to either that's too easy for you to say something like that and an insult to the KDE Plasma developers who are volunteers and spend their free time working on such a big project. As a general rule in software there will be bugs in x.0.0 versions, because they are new releases of a major version. AFAIK LMDE is based on Debian stable, would find it strange if KDE Plasma 6 is already available in Debian stable.