OS3.1 adds many enhancements, some more obvious to the general user than others. I can't say I've ever had 3.0, however upgrading from 2.04 to 3.1 gave my Amiga the biggest speed boost It's ever had - In many ways.
Weather you should upgrade depends on what you do, and what hardware you have.
Do you use a graphics card? If you, I would say it is a definate must.
Do you only play some old games, and nothing else? Then it's probably not worth it.
If you tend to use more serious software, it probably is worth the upgrade.
If you use quite modern software, I would say it is pretty much necessary.
Some developers will eventually start to produce software for newer versions of AmigaOS, and MorphOS, and for that reason, if you intend on running newer software, I would suggest you buy the latest you can afford and use.
:-)
