Not the thread for this, but I'll bite: they're rumored to be competitive with Intel in terms of IPC (=performance per clock speed), while being significantly cheaper for the same amount of cores.. Possibly lower power, but that's debatable - AMD specifies TDP in a different way than Intel, and AMD has shown a comparison between an engineering sample 8-core Ryzen chip and an Intel i7-6900K with only a few watts separating them in a similar workload (the top-end 8-core Ryzen is rumored to have a TDP of 95W, while the 6900k is specced at 140W TDP, but again, Intel and AMD specify TDP in different ways).
It's the price/performance ratio and the fact that we might finally have some competition in the CPU market again that's got people excited. Also, all Ryzen chips are unlocked for overclocking, and they have some new and exciting features (XFR or Extended Frequency Range ~= more or less automatic temperature-dependent overclocking, is chief among these).
Also, Ryzen gives you the option for more than 4 cores/8 threads on a consumer platform, while Intel limits this to its "enthusiast/prosumer" X99 platform, which is significantly more expensive (both CPUs and motherboards).
For more information: check out one of the roughly a dozen threads here concerning Ryzen rumors. Or just wait a week or so for launch, reviews and the like. By then we'll actually know things, rather than have leaks, rumors and speculation.