I entered an AIPA and an APA here on HBT in an unofficial competition. I got no prize, but some good feedback (not great feedback, though, as some of the judges could not be bothered to describe their tastings too well). The feedback I got basically mirrored my own opinion and pointed me in the direction I should look for improving my beer.
I also entered that IPA in a local homebrew competition and it took 3rd place. The BOS was another IPA. The only other IPA entered out of 15 beers. I got a couple of cool prizes and some gratification, but no written feedback. I got to talk to one of the judges during the beerfest and all I remember is that he said they all noted that the beer was "clean". Maybe I had too much beer that day to remember, or maybe he did... Or both...
Anyway, the brewmaster said I coudl talk to him and get some feedback directly, so I should probably head over there soon and talk to him about the competition over a few pints.
The win was bonus, because I really only wanted someone else's feedback. What I've got has been nice, but I think I could have done better in the feedback department. That is why I've entered a problem beer in the HBT competition. There was only room for one beer, and so I chose the one with an off-flavor that seems to be more common for me. I have an idea I know what is coming and if it turns out true, then I have something to work with. Otherwise, I may have more than one thing to think about.
I'll be using these to improve my beer and at some point will have improved enough to enter seriously, just for fun. Remember that oftentimes, the top beers are all great beers, and sometimes it just comes down to how many judges preferred that one particular beer that day. At the local competition, the Brewmaster said that he had a completely different take on a particular beer than the actual judges, but he was not judging, so his opinion didn't count.