And in any case, Fallout 3 is in many ways an evolution of what STALKER kinda' was. They're certainly different, but I can see why some people wouldn't dig STALKER, and would hence recommend they try FO3 as a suitable alternative. Personally, though, I loved them both.
I agree with you.
In terms of share difficulty, I think STALKER: Shadow of Chernobyl is a hell of a lot harder than FO3 was -- by a damn mile. STALKER: Shadow is tough at its default, as is. And well, Clear Sky is EVEN harder at its default settings over Shadow, since the AI's even more accurate than it already was (which was pretty damn accurate, in the first place) -- and if that wasn't enough, the new grenade-tossing feature makes it even much tougher in Clear Sky. STALKER: Clear Sky is basically for the STALKER: Shadow expert.
Also, I think FO3's storyline-plot, actual storytelling, and especially the voice-acting is much better done than both STALKER: Shadow and Clear Sky. Also, I think it might be a lot easier to say get lost in STALKER games than FO3, since FO3 is pretty clear on its main quest -- since you basically follow the quests involving your Dad and The Project Purity. STALKER: Clear Sky seems a little more straight-forward and obvious for throwing main quests at you when compared to STALKER: Shadow -- but still, neither are nearly as straight-forward as FO3. At times, STALKER: Shadow will throw quests at you -- but you're not really sure if it has to do with the main quest or not; and you won't know until you are into that quest (if you actually do that quest).
***SPOILERS from STALKER: Shadow.****
***SPOILERS on Who Strelok Is****
I mean, I never would've expected one side quest (you ain't forced to do), which I didn't do the first run-through, but I actually did do on the actual 2nd run-through would lead you to finding out who Strelok is -- which is actually YOU, the player.
STALKER: Shadow and FO3 are both excellent games, though -- I agree.