I've never actually played the Witcher games, despite owning them, but I loved this show. I wouldn't go on to say it's perfect for everyone, but I thoroughly enjoyed it myself.
If you're going to watch it. Do yourself a favour, and don't compare it to anything else, just enjoy the show for what it is.
I don't really know how Geralt is in the games, but I thought that Henry Cavil absolutely nailed the role he was playing within the world. I didn't need Witcher game or book knowledge in order to enjoy the show. The cost of this of course is the storyline has to start out slower than I think some would like in order to introduce a wider audience to the world and the characters. However, despite it being something of an investment into hopefully even better 2nd and 3rd and perhaps even further seasons, it was a genuine pleasure to watch