We've entered many wines over the years, and it's definitely a mixed bag. We've gotten a lot of really good feedback that really helped educate our own palates; a good example is a zinfandel that had a subtle note of what we tasted as a root beer kind of thing (not unpleasant), and all 3 judges commented on the slight oxidation and we were like "oh yeah I guess that is oxidized". Although they have a whole lot of judges who are familiar with fruit/country wines, mead, etc... it's fact that all wine competitions are biased towards vinifera grape wines, so feedback can be iffy on non-grape concoctions. If you can afford it, it can be informative, and you might get a medal out of it (which in my opinion is just a stamp of approval that you've made a wine with few to no faults, that someone else enjoyed).