Just came here after returning my Switch, primarily because i was so displeased with the controllers, as well as the size of the screen, for the price. Amazon can somehow push a 10.1 inch tablet with 64gb ram out the door for $189 (the new Fire HD 10 as of 1/8/2018) but Nintendo somehow has priced this system, which by all counts has rather mediocre tech in terms of gfx, at $300. Maybe i'm just too poor to enjoy nintendo anymore but given that I had almost 0 use of the screen because the one game i had played with it, Zelda, was almost illegible on the Switch Screen, text too small, but the joy cons... those broke my hands. I'm not even a very large handed person, but after 2 hours my thumbs both cramped and the center of my palms were on fire.
Ultimately i'd say the pro controller would be necessary for adults because of the completely ill-fitting controllers, but maybe they work for more people than i would believe.
I'm now holding out to buy the Switch once Nintendo releases the Switch XL, which i hope will have a decent size screen, retooled controllers -- for good comparison, the travel of the joy con's analog sticks is about 1/3 of what you'll feel in an xbox one controller, and it is VERY noticeable during times when you want to have very accurate aiming or other subtle movement. The buttons feel really cheap too, just not a very good travel to them (also lower than the button travel on either the ps4 or xb1 controller). Because of this, i would highly recommend, to the point of saying that it was absolutely necessary, to have the pro controller if you plan on playing for extended sessions, but only dive in if you're comfortable paying these prices. I was not, and I hope that by the time the redesign is out the cost will have dropped $40-60 as well.
It will hurt me to know that i'll probably see Bayonetta 3 and Metroid Prime 4 before i'll be playing the switch again, but it's just too costly of a hobby, i've been spoiled by PC gaming and the incredibly quick time that games tend to go on sale at 50% or more. I'll feel better when it's less than a $300 buyin at the outset.