No problems with mine sine I bought it in Nov despite the article today in the blog about how 7.1.1 has really improved it. It might have but no troubles here.
It always works for me and has never missed although even updating to 7.1.1 it does have it moments of being a bit slower than Apple claims speeded it up and had better recognition. I might delete and redo it as I use my right thumb only it still works great.
Saw this on another site and it seems like iMore found out about that article. Here's the link to make Touch ID work perfectly "every time". It's supposed to always work. http://m.imore.com/touch-id-not-working-you-heres-fix
Works pretty well for me. Sometimes though when the fingertips are a bit oily, I have to try it once or twice more than normal. But even then it works quite well. I seem to have developed a natural habit for it.