In some way, I share you deception about class mechanics but as I said, it is "relative".
I played on the first Nostalrius, and I was convinced that classes were fine. I mean 99%-100% fine. Remaining problems were not about a specific class but rather a game mechanics. Example: hitbox management in PvP, path-finding for pets in some circumstances...
Now, I see there are some class issues on Nostalrius Begins. Those are not game-breaking problems, but still, it's annoying, and not expected.
As a druid, for example, I figured out that the bear form does not give the right amount of bonus HP.
There are two possible origins for theses problems:
1) Latest improvements made on Nostalrius Begins before the launch had side effects that have not been detected during test sessions.
2) They were there from the beginning (mangos zero origin version) and have never been detected.
To be honest, and I am a little ashamed about it, but for the druid bug example, I think it was there from the beginning and we just never noticed it.
The bug was not visible at level 60 because the HP bonus matched the description we had found. At low level, however, I personally never checked. The deception about class mechanics is above all a deception about myself and other testers.
That's why I insist on the difference between bugs reported with 100-200 players and bugs reported with 5k players. Even if you have a very high self esteem of yourself as a tester, it will not prevent some bugs to be unnoticed.
What matters now is to report those bugs (looking forward bug reports section to open), and if Nostalrius dev team is true to itself, they will be fixed. Be sure that class bugs always are quite high in priority order.
Of course, we can't expect a better service than Blizzard themselves. And if I am wrong here, then another concern may arise: will Blizzard tolerate a private server to perform better than they do?