I've recently gotten back into the CoD series with the release of MW having not played it since Black Ops 2, and I've got to say that the game overall is VERY fun and very good! All microtransactions (bundles, paid battle pass, operators) are completely optional, you don't need access to them to play the game to its fullest extent. The free battle pass and paid battle pass are shared -- you get access to the new guns and things simply by playing the game. Anything that is locked behind a paywall is purely cosmetic, and it's not really an in-your-face type of deal (I have not purchased the paid battle pass and have no intentions to do so). I'm not going to write a huge ass review here, but I've enjoyed playing Spec Ops, campaign, and multiplayer (especially with crossplay!).
With Warzone, it seems that the microtransactions are the EXACT same as those in Modern Warfare -- everything is shared between the modes. The fact that Warzone is FREE to play (without owning MW) and doesn't have any additional game-altering microtransactions is honestly pretty awesome. I hopped in a game today and actually really enjoyed the MW spin they put on it (the use of shops in specific locations, an in-game economy, a 1v1 Gunfight in Gulag Showers when you die early in the game, the ability to buy back teammates spawns, etc.). There's been a lot of good changes to the traditional first-generation battle royale formula and it's a very fresh type of game (and much more refined compared to Black Ops 4's Blackout BR mode!).
Overall, very happy with the direction this game is taking, and I hope IW continues to support it with solid updates.