I bought that adapter, because I wanted to keep using my good old, high quality, corded earphones. It technically works, but it's not a nice experience. The adapter looks and feels out of place. It's the only white part in the setup (can't buy it in black), the cable is thin as a hair and feels like it might break soon, and I now have the additional plug and socket on that cable, which makes it awkward to put the phone in my pocket.

The adapter is annoying enough that very few people bother, and Apple knew it. It's also a bit flaky. Sometimes my phone doesn't detect it at first, or an inline mic doesn't work.