SPOILERS Please note, this isn't meant to be a discussion of 'why' Gus kills Victor. I get the logistics of it- weak as they are. This is more an assessment of what the character of Gus meant for the series and why I feel this episode in particular ruined that somewhat.
I've just watching season 4 of Breaking Bad and, whilst I still think it's easily the most finely crafted show on television in recent memory, the box cutter episode seriously bothered me.
To my mind, it took what was a genuinely novel, fascinating, and original character, Gus, and turned him into yet another Drug Baron; albeit a uniquely machivellian one (yawn). The whole scene just came across as lazy writing to me- something I never thought I would be saying about Breaking Bad.
Gus originally came across as a maverick- the prime mover several steps beyond everything and every one in the perfect guise of a mild-mannered owner of a series of commercially successful fast food joints who could, in actual fact, see the grand design behind it all. He was certainly not one to get his hands dirty. More than that, he also appeared to have adopted somewhat of a utilitarian approach to his particular line of work- one might even class him as a libertarian. There was something awesomely 'red hood', or, at a stretch, 'V' about the guy to begin with (that particular scene where he casually splits the mobile in half at the end...wow). He classed the twins, and the rest of the cartel by proxy, as 'animals'. He was not one of them.
I'm not at all saying that he was a good person, far, far from it. He was, however, supposed to be a strategist. We rarely, if ever, get to see dealers of this order portrayed in entertainment. By simply reducing him to a killer who can stoop to basic intimidation, the writers have totally ruined the mystery that was the Chicken Man. I feel they squandered an immense amount of potential here, not to mention halted any chance of further character development. They had a chance to do something truly different, even profound, with this character and they sort of blew it.
Still loving the series though ^_^