The game is fantastic however:
When you have a game full of players with brand new accounts out-fragging the professionals, you know there's a serious problem.

This game faces a cheating epidemic, it is by far the most cheater infested competitive E-Sport and Valve refuses to tackle the problem effectively.
At the top ranks, there is likely a cheater on one team or the other at least every second match. The trust factor system does near nothing to combat this, in fact, it often time punishes strong players who are regularly reported.

I know several, who went over a month cheating, sometimes with free, publicly available cheats, before being banned. They can avoid such bans through two primary methods, play too irregularly to go to overwatch (generally 2/3 games or less a day) or alternatively, not play well enough to be reported frequently enough or look "blatant" enough to get overwatch banned.
Cheaters who regularly drop 30+ kills are usually banned by overwatch within a week. Though sometimes they can avoid this for weeks or even months, this is however, rare.
If you are planning to play Valve's matchmaking and climb the ranks, I cannot with good conscience recommend this game due to the sheer number of players using external software to gain a competitive advantage.

The game at it's core is excellent however, easily the best competitive FPS, if you play FaceIT or ESEA (while there are still cheaters, they are far and few between) you will have a substantially better experience, these services provide players with the experience they deserve, it's just a shame we must turn to third-party companies in order to enjoy the game to its fullest!

I would like to lastly add, I have hour boosted my account to increase my trust factor and face less cheaters in Valve's matchmaking system. This has had a positive impact on my experience thus would encourage others to do the same (if you do not mind your hours not being a true reflection of your experience in the game). My real playtime in Counter-Strike: Global Offensive sits at ~2200 hours at the time of writing this review 09/07/2020. This translates to my shown playtime on Steam sitting at just over 1600 additional hours, than my real game experience.