linux的好处在于its flexibility

you can change it to whatever you'd like it to be. tired of kde, try gnome, e17, *box, dwm, ...etc. if you are geek enough, disable gui completely. if you don't want anybody to access your system from outside, lock it down completely. if you think their vm implementation sucks, change it or write your own. the kernel source is right there for you. linux provides possibilities, where do you want to go from here? it's up to you.

generally speaking, ubuntu is fairly safe, even access to the local X from outside is locked down. for new users, it's not a bad choice.

btw, don't use linux.org. it's too old. use distrowatch.com.