I think the Klingons are crass, shallow, and bloodthirsty, for the most part, and that their so-called "honor" is a sham. The one major exception is Worf, who lives the ideal and not the reality.
Understand I think MY favorite race has its flaws. Major ones. But I think they are much more fascinating than the Klingons, myself.
Problem with the characterisation of the Klingons is that for the vast majority of the time, we only get to see their soldiers and their military (something that's also a problem with the portrayal of the Romulans, who got far less screen time), so we only know the mindset of that caste of their society, and very little else. The only other snippets we know are that they make coffee that's quite popular, that their opera is somewhat cross-culturally famous, enough that Jake has to study it in high school (perhaps a Shakespeare equivalent of the 24th Century).
As for their bloodthirsty nature and their 'honour', I have a feeling that their aggression is something that's overridingly instinctive, to the point that as a civilization, is much closer to destroying them than the Vulcans were in their pre-Sarek days. Kahless, I believe, knew this, and used his teachings of honour as a way of trying to rein in and channel this natural bloodlust. Note, that he is stated to forge the first Klingon Empire (this was the days before Klingons hit space, so presumably, it was a nation state on Qo'Nos), which would be a good way of ensuring his teachings spread through a good number of his race.
As for crass, I looked at this on dictionary.com
1. without refinement, delicacy or sensitivity; gross; obtuse; crass commercialism; a crass misrepresentation of the facts
2. Archaic. thick; coarse
Well, not everyone in the galaxy can be as refined and eloquent as others

As for shallow, you'll have to elaborate on that one.
And yes, I accept there are flaws in the Klingons, they are certainly not a perfect race, woe betide you if they take out their aggression on you, they can be difficult to get along with, but then again, so are some other races.
Another point about bloodthirsty, is it better to be conquerors for resources, national glory or bloodlust? Does it really matter, since you are, after all, still invading others?
EDIT: If you want a real Klingon, look at Martok. After they found the real one minus his eye of course, since then we know it is him and not some filthy Dominion imposter
