Also, as has been stated before now in this thread, the Changeling Martok instigated this by cajoling Gowron to be aggressive. Note that once the Changeling Martok got killed, and the Dominion pushed the Klingons out of Cardassian space, Gowron was ready to re-sign the Alliance treaty. And in TNG, there were Klingons ready to break up the Alliance, but the Klingons punished them for doing so.
The changeling did NOT brain wash the klingon high council; he just convinced them to start a war without even bothering to mention this to the federation and then retreat from the alliance when the federation refused to submit to their bullying and support the war.
ONE changeling managed to convince the klingons to start a large scale war, to end their alliance with the federation and this is supposed to be a good thing? To paint the klingons as loyal?
I'd think of any major Alpha Quadrant power, the Klingons make the best and most trustworthy allies. Romulans are deceitful, Cardassians use treaties as rouses to re-group (as seen in the Wounded), etc. If a culture believes in honour, then it surely is dishonourable to break a treaty signed in good faith.
The klingons - at least, the vast majority of the klingons we saw - do NOT beleive in honor.
O, they repeat the word 'honor' once every 3 sentences. But their 'honor', curiously, changes with the situation, always supporting whatever course of action is most profitable for the klingons.
The klingons are bullies, pirates.
They built their empire by conquering other species (in the process, killing everyone who opposed them in the slightest) and exploiting their worlds.
During TNG they were in a state of 'frozen war' with the federation. See 'Aquiel' or 'Unification'.
And what's with their horrendous table manners?
You want loyal allies with a warrior nature? Look at the Andorians.