To make it short:

+ Core of the Game is good. Classic fast pace Arena-FPS with lots of fragging
+ I like the Champs, theire abillities and how they have diffrent movement styles that represent past Quake games (Strafejumping, Bunnyhopping, Doublejumps, Walljumps, Crouchsliding, ...)
+ The abillities and stats of the champs bring a new strategic element that add to you classic aim + map control + enemy awareness skillset
+ The game looks nice and is some welcome update to the very dated look of QuakeLive (I never liked playing with low-res and Brightskins, I want my game to look good not only functional)

- After years of Beta and Early Access game has still many technic problems. Server Connections get laggy, desyncs between players make shots register around corners, player popping out of nowhere or the game stutters in critical moments when 3 or 4 players meet at one point of the map (its always frustrating if you loose because of it, but game is fun enough to bear with it)
- Content Development for the game is very slow. After years we are still stuck with more or less the same map-pool. New Modes have been added (like Capture the Flag) but have only one map that is really made for it. Most of the time there are always the same maps for you to play Duel, DM or TDM. A map cant be optimizied for playing with only two players or eight players.
- there is absolutly no support for community content. So no fanmade maps, which is really sad because a lot of great maps for Quake 3 where done by the community.
- The loading times are often really excessiv. And that not only before a match (when a lot of data has to be unpacked and loaded) but also after every match, so on lets say 10 minutes of playing you spent a good 5 minutes of waiting.
- Last but not least, there is an Ingame shop und Ingame-Payments with real money. Which is not necessarly bad itself, but I cant help but feel that a lot of the problems the game has results form this. The lack of content for exemple seems to stem from the few developers that still work on the game are more busy with creating cosmetics and designing the Battlepass then actually gamecontent (like maps), and even that get more lackluster every season and is now only made of reskins and recycling of older content. Also the use of real money in the ingame shop surely is one major point why the game is so locked and secured against all modding.

So in the end Quake Champions is still at its core are good Arena-Shooter and a lot of fun to play. But it also has some very serious problems and it seems to me quite a few of them are very homemade by decissions that put the Ingame-Moneymaking over the development of the actual game. Until they fix the most urgent problems like the ratio between playtime and waitingtime in loadingscreens and menus or the lack of proper maps for the diffrent play-modes playing the game is a constant up and down between enjoy and annoy.

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EDIT:

Nearing a 1000h of QC now and I have to change my opinion from not recommend to recommend.
Yes, some of the problems got solved, like they put up more servers and the game got some optimization, but no, the crucial points still remain. Lack of content, slow development, wrong priorities... BUT if you want to play quake-like AFPS what should you play?
You should play Quake Champions!
It is still the best Quake Game out there at this time (yes, it is better than Quake Live!!!) and it is still the best quake-like AFPS Game out there (yes it is still better than Diabotical! May change in the future...)

And finally, how could I not recommend a game I myself have played for nearly a 1000h? It must be a fun game in the end.