It's true that Nvidia and AMD has better raw performance numbers, but for some reason - despite all the years gone by since both Nvidia and AMD pledged support - both Nvidia and AMD drivers still suck IMHO. Nvidia seems more stable than AMD, but overall less stable than the standard Intel drivers. It seems there's always something that does not work properly with either of the drivers, being trouble waking up from suspend/hybernate, glitches/hangs (which destroys any notion of "fluidness") and occasional total driver breakage with new laptops, new linux releases or similar.
The only annoying thing is that even though the intel driver works nicely, there are still many things it does not support. If you're using Chrome, type in "chrome://gpu" in your browser and count the number of colored lines in the first section. On my f* up Nvidia Optimus system (yeah, current office standard, oh the number of hours I've wasted on that computer) I get 5 greens, 3 greenorangy and 3 reds. For comparison, my Macbook Air Pro running OSX I get 11 green and 1 greenorangy. I do not have my pure Intel laptop handy, but if I remember correctly it has very few if any greens at all. That means Chrome is doing all the heavy lifting without much hardware support. That often means it's the same for most apps, possibly except the desktop environments themselves who seems to do a decent job on linux desktops already.
Anyway, here's hoping that there will be decent Intel drivers for Linux laptops sometimes in the near future, so Chrome and other apps can get more greens and comparable general graphics performance as Nvidia and AMD on OSX and Windows.