IMPROVMENTS:
Well it gives you a few advantages if thats really what you want to do. How much extra is it?
1. Integrated SSE3 multimedia instruction sets
2. Mismatched DIMM support (ability to configure and use different size DIMMs on the same channel)
3. Improved memory mapping (more efficient use of memory space)
4. Improved memory loading (can fully populating the memory with double-bank DIMMs with no slow down)
WHAT I THINK OF THEM:
So, you'd get a few advancments if you really want to do it, but I wouldn't think its worth sending back my Winchester core for it, not if its a big price difference.
The SS3 support might speed some programs up though,and might help for things like multitasking which AMD lacks in, with the memory enhancements too working along side this for programs to use.
You wouldn't notice any other differences though, as its still running off the 90nm process, and still about the same running temperatures (might be a tad bit cooler but not much when working since I think they've made some minor changes to the core).
CONCLUSION:
So you might notice some changes in speed, but its hard to tell really.
I'd advise people to get it if they hadnt got an AMD core as yet and wanted to update to one of the newer models, but for someone who already has a Winchester core...I'm really not sure...