There are various ways to try Debian before you ‘buy’ it. One is the live CD either Debian or Ubuntu, and the other is to run a self contained install from a USB drive. Seeing as these handy little gadgets are getting larger and cheaper as time goes in, this is a pretty viable method of doing things.
When I first tried this a year or so ago, I found it almost impossible to figure it out. Luckily a little further down the line, it is as easy as it could be. If you can complete an install on a normal hard drive, you can complete is on a USB drive. If I can do it then anyone can! Previously there were lots of command line action needed to get anywhere with a USB install. Now it’s pretty much the same as a standard one!