It really depends on what you want it to do.
I've used one for about three years now, and it does several things very well.
1) Noise reduction
2) Weak signal CW
3) Weak signal digital
4) Wiping out adjacent signal QRM
It is less helpful on phone, though careful tweaking can bring a weak signal in more clearly. And the noise reduction helps as well.
I like it a lot with my older rigs (FT-890 and FT-900), although mine will soon be "surplus" as I scored a good deal on a Timewave unit.
Member: Backyard Engineering Group