I've only played through tiberean sun once, and that was a good while ago, but my impressions on C&C in general are that it's usually a fairly relaxed pace that allows the player to use his preferred general tactic and complete the mission in his own time, but there is often a critical segment (most commonly at the beginning but not always) that can get you steamrolled if you're not prepared for it or react quickly and precisely.
as for myself, i just finished STALKER Call of Pripyat. once again i find myself disagreeing with what seems to be the general consensus of the gaming community. i thought that this was the weakest of the series. it was enjoyable, sure, and the game mechanics were ironed out pretty well, but there just wasn't much there. the story was the least interesting of all of them. it felt more like a cluster of side missions that were kinda shoehorned into a main plot. only three areas with not a whole lot of interesting in them, especially pripyat. i thought this is where the game would finally take off and get out of what felt like the intro/gather equipment phase and actually develop the plot, discovery, and throw in an actual well-defined adversary. but when i got there it was just a few more "side mission" plot missions, some hints at major reveals that were never explored, and..... wait, we're leaving? that's the ending?
according to steam i put 58 hours into it, but i don't think i believe that. i must have spent WAY more time trolling around for artifacts than i realized. or chasing down phantom leads that seemed to indicate there was much to be explored/discovered but ended up going nowhere.