What would it take for you to consider Boehner a "failure" as Speaker?This is a great question, since I often say that Boehner is a pretty good Speaker, but don't always really explain what I mean.
So, what would make Boehner a failure? First and foremost, if his own conference turned against him (especially early in his tenure). That would be pretty good evidence. But you're probably thinking: there was a semi-revolt against him at the beginning of this Congress! Well, yes, but I think that's hard to hold against him; those who opposed him were from the fringes of the party. There's not much any Speaker could do, as far as I can see, to control that. What I'd take as a sign of failure would be if the revolt came (as it did against Newt Gingrich and Jim Wright) from the party and conference mainstream.
Both Newt and Wright were "too strong" -- that is, they tried to be party dictators in the House, and Members rebelled against that. It's harder to find objective evidence that the Speaker is "too weak." That was the problem with Tom Foley (and perhaps Hastert; his Speakership is harder to characterize because of his relationship with Tom DeLay). There does seem, however, to be general consensus that the Foley House was often unable to pass party priorities despite seemingly having enough votes to do so. I don't think that's really a problem for the Boehner House; the problem passing things appears to be based on real party divisions. One might argue that the Farm Bill is something that the overwhelming majority of the conference would like to pass, and that Boehner has failed to figure out a way to make that happen. But I can't really think of another example.
A third problem would be if the sausage-making is unnecessarily ugly. Boehner might be faulted on that one; he's had multiple episodes in which bills had to be pulled off the House schedule at the last minute, or even brought to the floor and defeated. My general sense, however, is that this isn't really that big a deal. And that Boehner deserves more credit for avoiding a truly damaging fiasco (a long government shutdown, or a debt limit breach) than blame for a bunch of awful-looking false starts.
Basically, I think the House Republican conference is a mess, and that it's going to look bad no matter who the Speaker is. There seem to be a dozen, maybe two dozen, Members whose primary motivation appears to be differentiating themselves from their own leadership (in order to prove that they are Real Conservatives and not sell-out RINOs). It doesn't appear to be issue-based, so it's just about impossible for any Speaker to cut deals to make the problem go away; indeed, the form of the opposition is hostility to any deals, regardless of policy content, with anyone. And on top of that, almost everyone else is terrified of distance between themselves and the fringe -- and terrified of agreeing with a president who, given divided government, they're simply going to have to cut deals with in order to get anything done. Those conditions make the Speaker's job impossible, and unless Boehner is responsible for those conditions -- and I think he is not -- then it's hard to blame him for the consequences.
I'm probably going too long on this, but I should add one more thing: if it turns out that Boehner does in fact retire after this term, and it further turns out that his retirement was involuntary and that mainstream Members of his conference wanted him out, then I'd have to revise my thinking, perhaps quite a bit.