Almost every game runs on it Tons of programs run on it More Cusomization on the computers is possible
SPYWARE, VIRUSES, ADWARE GALLORE! Not as "nice" looking Error message after error message
Relatively lightweight, sleek design. Widescreen display. Quick and easy to upgrade the RAM and hard drive. Quite fast when running "Universal" applications, as fast as some MacBook Pro models in some situations. Gigabit Ethernet standard. Built-in iSight camera for easy video conferencing. Clever "MagSafe" connector helps protect the system from damage. Relatively inexpensive.
Heavier than the replaced PowerBook G4 12" models and some competitive Windows notebooks.
Glossy display casts a glare in direct lighting.
Processor cannot be upgraded.
Most distributions are free (Open-source). Good for servers. Some distributions have good user support. Some distributions allow you to test before installing (LiveCD).
Some distributions require some knowledge of how Linux works to get the most out of that distribution. Not many companies make programs for Linux.