There's really no comparison actually. Both cars are very different.
The Zed was a little more agressive but missed a little "punch". The Boxster is less agressive, but a little more powerful.
The design is very different as well, a little due to the age difference as well (the Boxster is 10 years older).
There's a significant difference in technology as well, again, probably due to the age difference as well. The Boxster needs a little more time to warm up, needs a little more time to find the right rpm at idle so sometimes you have to play a little with the throttle, which is also an older system with cable instead of an electronic throttle like the Zed.
But overall I'm quite happy with the car. I always loved the design and sound of the Porsches in general. I had the exhaust altered by Carnewal, which is a big plus in sound, sounds really good now, especially when the exhaust is hot.