It's a handheld, not a home console. However, the 3DS isn't a good base to say "maaaasive upgrade". Low end phones today are beating 3DS on graphics quite handily.
But Vita still has mobile phones beat, not in performance but in the actual game graphics. Switch is several times more powerful and on par with modern Apple SoCs. Considering how mobile phones have absurdly crappy APIs and are extremely badly optimized (come on, Vita has 50 Gflops and still beats games running on 300 Gflops phones), Switch will be substantially above mobile devices.
It will probably deliver PS360 to Wii U visuals on the go and better than Wii U visuals when docked. That's quite good.








