since this thread got bumped, I HAVE gotten several surveys, and I always put UAL low.
What I find interesting is that they now have (perhaps always did, and I just missed it) a "net promoter" question. Its right after "how happy were you with this flight" they ask in essence "based upon this experience how willing are you to recommend United to other"
I assume they are getting some very bad numbers.
I think a more open ended follow up question not about that flight, but the entire package UAL is offering, might be useful, but I can't really say that they survey is useless. I'm sure they are getting a useful net promoter scale and identifying the number of complaints by areas (such as IFE, food, etc).