For anything above Haswell the only things that matter are core count, frequency and whether it has hyperthreading. There haven't been any notable improvements to per-core perf since Haswell.
I also have the same impression. Looking at various Passmark CPU benchmarks Hardwell has been the last big upgrade (but also only when considering battery usage). Since Haswell I have seen any major must have big improvement. It would be great if Intel will develop a true 4 core i7 processor with TDP like 18-28W... I also have the feeling Intel is getting lazy (since the have the monopoly on mobile desktop CPUs). Especially when comparing speed of innovation to ARM mobile phone processors.