I have the D4 and it is awesome. As with anything, it takes a little
getting used to it to get good at it, but I'm not one of those that feel the
Leigh was difficult to figure out. Bascially, if you can follow
instructions (with pictures, no less), then you'll do fine with this jig.
The manual is extensive, but that's not to say complicated. The jig itself
has a lot of versatility, so that lends to varied instructions depending on
what you are trying to do. For making simple through dovetails or
half-blinds, it is VERY easy (IMNSHO).
I recently bought the finger joint attachment and have used that a few times
now, too. Not inexpensive, but it has the same type of flexibility that
I've come to appreciate from the D4 and so I felt good about the purchase.
If you've seen it in person, then you have the best perspective on how
satisfied you will be with it. I highly recommend it.