I often describe Witcher 3 to others as "objectively the best game I've ever played". Sure, I'm using the term "objectively" incorrectly, but what I mean to say is "No other game has managed to master every element of its experience nearly as well as this".

Story is incredible, I loved every moment. Side quests are awesome, each one is important and some even tie into the main quests. Small, meaningless DLC is free, and the only DLC that costs money is such a gigantic expansion it could be its own game - absolutely worth its cost, and nowadays CDPR makes the GOTY version with the DLC at the same price as the main game alone during sales. Combat can be as easy or difficult as you want, while not as mechanically strong as Dark Souls it's very enjoyable. On harder difficulties, you're going to want to know as much as you can about brewing potions and oils for your weapons to survive, and you will want to read about creatures before fighting them to know their weaknesses, while easier difficulties make it so you don't need to do this - which is good, some may not like this. Graphics are beautiful for 2015 but start to show their age a bit in 2019 - largely fixed by mods. And of course, mod support exists and there are some really good mods out there - while not as diverse or expansive as Skyrim's.

One element I hear many don't like is the lack of a customizable character; but there's an important reason for this. Unlike Skyrim, you're not some random person who suddenly means something - who has no backstory, no history, and didn't exist prior to the start of the game - in effect, you are a stranger who became special for no real reason. Not a single character you meet will know anything about you, everyone you meet it will have been the first time you've met them and your relationship starts there. NPC opinions of you are formed on the spot, if someone dislikes you its rarely for a good reason - it's because you exist, and they don't like you.
Geralt has a backstory and is understood by the people; he didn't spontaneously exist one day. Characters from the previous games know who you are, and those pre-existing relationships waste no time in skipping to the point of what you're doing. They have their own opinions of Geralt that they didn't form in the first 5 seconds you saw them. If someone dislikes you, there's a reason for it; Witcher's are generally disliked, and we can't forget that Geralt is the 'Butcher of Blaviken'. That's not to say you need to play the previous games or read the books, but it is to say that there's value in doing those things if you care about role play.

Elder Scrolls, Divinity, Dragon Age, you can make the character you want and the game tries to accomodate that, with such diversity it can be difficult to make role play different and engaging.
Witcher? You can make Geralt the kind of person you want, but no one forgets who you were before; and role play is all about being the kind of person you want Geralt to be. It's a different experience, for sure, but makes interactions much more meaningful - and Geralt is significantly more memorable than any custom character I've ever made.

Witcher 3 has firmly cemented itself as one of my most favorite games of all time, to the point I even own all of the books. I strongly recommend it to any RPG fan, especially those interested in an element of Story. CD:PR has truly outdone themselves, there's a reason it's still nominated for GOTY awards 4 years after it came out.

Not QUITE a classic cRPG experience, because it's turn-based combat as opposed to the realtime yet pausable combat of Baldur's Gate or the more modern Dragon Age. But I actually prefer the turn-based combat - something I normally dislike in any game.

Story didn't pull me in, but it seems many enjoy it - my friends sure did.
100% co-opable with up to 4 people (or more with mods) and lots of content to play and experience.
Some puzzles are a bit cryptic, but for the most part with 4 people we didn't have much trouble.
Can be quite difficult combat a lot of the time - definitely a game you want to prepare for combat with potions and other items for assistance.
LONG, this is no short experience, if you like it you've got a whole lot more to go - and while I don't think it has too much replay value in terms of differences, it definitely has enough going on to justify multiple playthroughs if that's what you're looking for.

And the switch version cross-save support? Icing on the cake.