So, as a long time Hitman player (there from the start), this is by far the best one...but.
The big "but" is the price. I can not recommend the game for the normal retail price.
So get it on sale only!
What you get:
The complete Hitman story (the remake one) from Hitman 1 to Hitman 3. So you can play to whole story in one game. As is the format with the the new Hitman series you can play (and is highly advised to) any mission multiple times and explore the many different possibilities to eliminated your targets, complete challenges and so on.
The new addition that comes with Hitman 3 (or Hitman WOA) is the Freelancer mode which extends this games game-play by many, many hours. It gives you never-ending stream of missions to complete, get weapons, tools. As you progress the mission get harder and harder, you only have some info on the targets but must find them on the maps and identify them properly to successfully eliminate them. If you fail, all your progress till then and your mission weapons are lost and you need to start from scratch....but this time the enemy is already alerted to you. So you can imagine it is more high stakes then the classic SP.
So if you are a stone cold killer and or just like Hitman, go for it (but only on sale)!