Let's start with invasion of your privacy; from gnu.org [1]: "As of October 2012, Ubuntu sends personal data about users' searches [2] to a server belonging to Canonical, which sends back ads to buy things from Amazon."
More at [3].
I don't know if this problem persists, but it's enough for me to choose a distro that never did something like this to begin with.
The good thing of Ubuntu is it's more stable than the other ones I used (Puppy, openSUSE,...), the last time I tried, Ubuntu booted ok with my Pentium 3, 128MB RAM, Intel onboard GPU.
The Ubuntu 8.x to 9.x sucks, but for 10.x and upper, it's cool again, at least, that's a good choice for Linux beginner :D
More at [3].
I don't know if this problem persists, but it's enough for me to choose a distro that never did something like this to begin with.
[1] http://www.gnu.org/distros/common-distros.html
[2] http://www.omgubuntu.co.uk/2012/10/does-ubuntus-amazon-lens-...
[3] https://www.gnu.org/philosophy/ubuntu-spyware.html