Robusta is great if you don't go with the low quality stuff. Good quality Vietnamese Robusta is very enjoyable (and much higher in caffeine than Arabica, which I think is a nice bonus).

There's also the possibility of hybridizing Robusta and Arabica to get the best traits of both. A few hybrid varieties, such as Catimor, have existed on the market for a while. AFAIK Catimor has some of the hardiness of its parent Robusta.

As always, you'll have the best experience if you buy whole beans and grind them yourself (or at least find a supermarket that lets you grind beans fresh). No instant coffee that currently exists will be able to compete with that.

Vietnam seems to like it, fine. Pretty popular in France and Germany, too. If you have ever had Bustelo, then you've had it.