Recs.
Updated
SpecsUpdate
Pros
Pro Great community support
As the most popular Linux distribution, there's a wide range of sources for support online if you ever need help, including the Ubuntu Wiki, Ubuntu Forums and the Ask Ubuntu Stack Exchange site.
Pro Just works out of the box
Lots of support for hardware, lots of pre-installed software, and a smooth install process means less time downloading drivers, less time digging through configuration files, and less time deciding on software to use just to get up and running. It also means less time digging through forums looking for support.
Pro Polished UI
Ubuntu is designed to be used by everyday people. Because of that, Ubuntu has tried hard to make a user interface that's intuitive and looks pleasant and clean.
For developers this means working on the same OS as your servers, but with the benefits of a UI designed for humans.
Pro Lots of support
As the most popular Linux distribution, there's a wide range of sources for support online if you ever need help, including the Ubuntu Wiki, Ubuntu Forums and the Ask Ubuntu Stack Exchange site.
Pro Use it on almost any device
Not just for laptops - Ubuntu was designed with tablets and touchscreen devices in mind, and with phone support on the way. Ubuntu also has Long Term Support releases, as well as a version oriented toward servers, so you can use the same OS at work or on mobile as you do on your desktop.
Pro Dedicated software center
The Ubuntu Software Center offers a GUI interface for installing new apps which is extremely easy and welcoming for beginners to Linux. But it should not be used by more advanced users since the method of installing through the terminal is much faster and easier after one is used to it.
Cons
Con A lot of the answers in the official forums come from inexperienced users with limited understanding of Linux
The community jumps in to help with hacks and quick fixes without understanding issues like security. Often advice like chmod 777
and sudo xyz
etc. ends up causing more damage than solving the issue.
Lack of pre-installed security software like app armour, SElinux or even an activated firewall allows the user to shoot himself in the foot and the community often provides a bigger gun to do so.
Con Custom PPAs required for most software
To get the most software available, user must add several PPAs to the system. That has major problems:
1) Terminal recommended for adding a PPA, which can scare away users
2) A PPA can potentially distribute malware by creating a "newer" version of a package than available in other PPAs, such as the Linux kernel.
3) PPAs must be recreated and re-added with every major system update
Con Relatively high system requirements
The default GNOME desktop environment is a resource hog which requires hardware accelerated graphics rendering in order to run smoothly, making out of the box Ubuntu unsuitable for low end systems and older hardware. Even mildly aged hardware, you'll get far better performance out of a lighter desktop environment like LXDE or XFCE.
Con Canonical does not respect Ubuntu users' preferences
In 2012 it became impossible in Ubuntu to move the close-window-button back to the upper-right corner of the window, where it always was before. To the questions of their users Canonical replied that they know better than users where it would be convenient for users to have the close-window-button.
Recommendations
Comments
Flagged Pros + Cons
Con Unstable
Some people pointed out that updating Arch is a high risk affair. And one should carefully read forums before doing it. The same is true about Ubuntu. Making system updates (like it was with 10.04 to 11.04) that screw so many things up became a routine. Even LTS releases should not give confidence that it will work.
Pro Wide range of software out of the box
The default apps available in Ubuntu cover the gamut of most anyone's needs. From music, video or office applications Ubuntu has an app that will cover the users needs.
Pro Simplicity
Ubuntu is designed to be used by everyday people. Because of that, Ubuntu has tried hard to make a user interface that's intuitive and looks pleasant and clean.