Nice. I actually am not a fan of the Z4 Roadster but the Coupé is much nicer. I think the long nose suits the sleek lines of the Coupé much better. It is a good alternative to the Cayman S. I even catch myself thinking about owning one myself.
The only negative to me is that it is less practical than an E46 M3 and doesn't weigh much less and produces the same power. That's from a purely power rating perspective. Style, fun, driving dynamics, etc are another matter. Thre are many subjective things to consider.