Just read the electronic shifting article on cyclingtipsblog and unsurpringsly the comments section is filled with the “why fix what isn’t broken” kind of comments. I am not going to go on and say how much better electronic shifting is compared to mechanical shifting. It is better but it isn’t going to change your bike into a rocket ship. What it is, is an evolutionary change to the way we shift gears. To me it just shifts gears. Whether it uses wire cables to do so or a motor is insignificant to me. The fact is it shifts gears at the end of the day. It provides a small advantage over perfectly tuned mechanical shifting systems and increases its lead once mechanical shifting systems start to wear and tear. It also allows you to ride your bike slightly differently to take full advantage of this new method of shifting. I could go on and describe how little the differences are but the basic point is, until you have being riding your own bike on a electronic shifting setup for more than half a year, you would probably not appreciate or pickup on the points i make.
With the ultegra Di2 available now, electronic shifting is more accessible than ever. If you are speccing up a roadie and you have the choice of a new groupset, i urge you to seriously consider the Di2 setups.