I would think like most instruments, it is often easy to play them, but more difficult to play them well.
That pretty much sums it up.
Daff (def, duf, tar, whatever) is one of the most basic instruments made in that its a single sided frame drum with no added elements (i.e. jingles, snares, etc). The question of complexity is about traditional patterns and techniques applied to the instrument.
That said, the traditional techniques are less complicated than other hand drums like kahnjira or tabla. And I might be willing to go so far as to say they are some of the easier ones to grasp (no pun intended) in the frame drum world.
Its the traditional patterns of middle eastern music that tend to throw people, as they are more linear and "melodic" than most western percussion patterns.
In the end I'll always say "go for it" as theres no reason not to try out new things
