All of my batches other than my partial mashes have turned out quite good to excellent.
I just didn't have the right equipment to do partial mashes, and I ended up mashing too high.
Oh, and then I had to dump 3 batches when the city switched my water source over to one with chlorophenol. So, I had to flush my pipeline.
But in general, if you follow the recipe you'll end up with good to great beer, and everytime has been a success.
I had some noob mistakes, like not getting the bottling sugar mixed in the beer well enough, so I lost a number of really really good stouts to over-carbonation, but the beer itself was good....
Ratio right now is probably 3:1 good:bad due to the partial mashes. If you account for the dumped batches, it's probably more like 3:2, but it was a good learning process.