For one thing, I like it very much.
However, after trying it out on a live usb on a machine from this year and finding the performance to be vastly better than on my Vaio from 2 years ago, I do wonder whether Ubuntu's marketing doesn't need to take more into account the fact that a lot of people are using Linux to work with older machines.
Ubuntu is stylish and a lot of fun when your machine is strong enough to throw it about a bit but like the other Gnome 3 DE's it feels heavy and awkward on lower spec machines.
Now, you will say "ah but there are lighter alternatives both within the Ubuntu family and without". And this is true. However, many new users still pass through Ubuntu and the Ubuntu concept and this forms their first impression. As the saying goes: you don't get a second chance to make a first impression.
It might increase the positive feedback about Ubuntu if potential Xubuntu or Lubuntu users were already directed towards one of those flavours at the moment of their initial contact with the Ubuntu concept (triaging).
Just a few thoughts.