To me is not exactly a handheld, more like a tablet with keys. A handheld would be the equivalent of a smartphone, pocketable, small screen... The Switch is too big for that. But I like mine.
I play it in handheld almost exclusively (only use the dock for multiplayer). My problem is with the games... Mario Odyssey was amazing (but prefer the level-based Marios, like 3D Land...), Oxenfree is amazing (my laptop can't run it), Mario Kart 8 Deluxe beats every other game in the series, Pac-Man Championship Edition 2 is ok (I prefer the first one or the DX+ version). That's all I have. My 3ds? Damn, way over 20 games, and like 15 more I'd like to get. And except for Mario Kart, every game I have on Switch I prefer the 3ds version... just wish the 3ds had a tv-out and maybe a 480p screen.
Sometimes I regret getting the Switch instead of more 3ds games, but I got the console with a bonus card for a store that doesn't sell ANY game related stuff, so it was almost free :P Still don't know why they had a Switch... And this year, man I want that Gamecube's Luigi's Mansion port, Metroid Samus Returns, Zelda A Link Between Worlds (yeah, I know, like three years late to the party). Buy somehow I don't want to spend more money on the 3ds, I want my Switch to succeed it... but Nintendo ain't helping me xD