He goes unnoticed because most people only watch the highlights of Barca matches. You see Messi netting in goals, Xavi and Iniesta making glorious defense splitting passes, but you dont see Busquets pulling the strings behind the majestic trio. He hardly does the final pass, but creates space with runs, one-twos, body feints and so on, but that doesnt get time on Sky News.
Whenever I read forums about him, even when ignoring the diving/acting jabbering, he still doesnt even get credit for the things he´s really good at, which is passing and creating space with runs. I´ve seen him called "lazy player, weak passer" and then "brilliant midfield destroyer" and I´m just thinking WOW, its actually the complete opposite.
I agree that if you put him on a more physical, counter attacking side, where his duties are more to break the opposition and make tackles all over the pitch, he´d be far less effective and just another solid DM, but in a possession oriented team with great passers in midfield, theres nobody better than him at the moment.