The sequel to Shadow of Chernobyl, Call of Pripyat does an excellent job of adding to the previous game's mechanics and making it a smoother experience. Issues from Shadow of Chernobyl such as item repair are now included without needing mods and other aspects are changed such as artifact hunting and a degree of neutrality with other factions (such as mercenaries and bandits). The game is perhaps more open world than SoC and the side quests are much more intuitive. Most importantly, the game retains much of its original atmosphere and you'll continue to explore the decaying wastelands of the Exclusion Zone.
With that said, the game does have some weaknesses. While it retains that atmosphere that made SoC great, it also (disappointingly) leaves you cut off from much of its namesake town of Pripyat. Regions you once explored in SoC such as the hotel, government building and the park with its iconic Ferris wheel are now only seen in the distance behind fences. The buildings you explore instead seem sparser and more linear. Likewise, human opponents are pretty thin in the game and most of your fighting will be against mutants. Sure, you CAN just start shooting people on sight but the different factions and uncertain nature of SoC felt much more exhilarating to me and winning against 'human' opponents just felt more gratifying than shooting umpteen mutant dogs and pigs. Finally, the ending felt rushed to me and less epic than the original breech into the forbidden CNPP.
Even with all that, Call of Pripyat still felt like a worthy successor to Shadow of Chernobyl. I would definitely recommend that someone new to the series play SoC first but Call of Pripyat will be a satisfying way to remain in the mysterious world of the Exclusion Zone a while longer. Call of Pripyat played well 'vanilla' without requiring mods (which is more than you can say for the buggy SoC) but there are multiple well crafted mods to dramatically change the world and keep things interesting for a long time to come. Shadow of Chernobyl was a tough act to follow and Call of Pripyat made it most of the way there; a recommended purchase in my book.