- Good security
- Fast, lightweight - doesn't slow down.
- Community support
- Lots of choice
- Plenty of software available
- And it's free!
- You need to learn that Linux is not Windows. It has a different structure and administration approach. You don't download and install Windows programs.
- You'll have to decide if you can do without one or two things - Adobe or Microsoft likely or maybe Turbo Tax - that will not run well or at all under Linux.
- Gaming still isn't as good in Linux although it's getting there if you use Steam.
- You might have to learn GIMP instead of Photoshop.
- There are a wide variety of distros to try. Some are quite frankly for experienced users so you need to stick with a mainstream user friendly one like Ubuntu or Mint until you learn more.
- Hardware will be a potential minefield so do your research. You'll be in a world of hurt trying to get Debian to work with some obscure wifi USB adapter if you don't.
- Using the Terminal is fast and efficient - not a return to the DOS days of 1985.
- There is lots of support out there but most folks who do it don't get paid - so they expect you to put in a bit of "sweat equity" and not just ask questions that have been answered many times in the past.
The learning curve is the main reason I never expect Linux to be as successful as a desktop as it is as a server O/S.
Android is a separate case - more idiot proof and similar to a Mac O/S. But it isn't free.