There is a big difference between a fad and a passing fad. Something that is a fad could be around for a long time.
What it all boils down to is individual preference with constraints. What constraints? It is a question of what you want to use it for. It is really that simple. People who are very mobile find them very useful. People who sit at a desk all day and type and click on a lot of things seem to prefer desktops. I'm getting a new desktop at work next week. Not a tablet; not a notebook. (The security people at work have noticed that a lot of portable equipment seems to disappear in comparison to desktops. They also don't have the security protocols in place to deal with critical personally-identifiable data (government data on individuals) being mobile yet.
So, the answer is: if you can find a use for a tablet without too many downsides for what you want to do, go for it.