This game had some critical stability issues, and I mean CRITICAL, it would BSOD and crash to desktop on me like crazy, horrible optimization, corrupt save files (Lost about 6 hours of my day there), game breaking bugs like at the very end you couldn't save in Chernobyl, otherwise Strelok would become invulnerable, and so on.
With that said, it is THE only game I would take all of this crap from, STALKER series have no comparison to anything out there, and to me they are the best games made in a long LONG time. The Master difficulty was just right for me (Yeah... I like my STALKER a little sadistic), customizable weapon and armor system was something really appreciated, the new artifact hunt thing was fun for me, and the increased amount of AP rounds available was also a great improvement.
Despite technical issues, I still love my STALKER, the reviewer probably got too frustrated with the stability of the game and numerous (I can relate to that), but in my opinion this game is superb.
EDIT: Two things I have to comment on the reviewer's conclusions are first of all, if you don't like if the game is too difficult then set it to easy, I prefer my games as hard as possible (increases playtime for me) and even some games on the verge of impossible. This is an acquired taste and obviously doesn't translate to you, but I really do hate when people bash games based on difficulty, just like what happened to GRAW2, brilliant difficulty, but bashed to death by angry reviewers.
My second statement refers to the ammo bit, I don't think we played the same game, because I carried at all times a SGI-5k (modded to 5.45), an Avalanche, and a GP37 I think, and I usually had ~1100 5.45 rounds, ~900-1000 5.56 rounds, and ~600-700 9x39 rounds (This is total ammunition available by adding together regular and AP rounds). I can honestly say every time I was running "low" on ammo (About 400-500) I would just switch to a different gun and be restocked in no time. If you didn't notice, the trick was to pick up every rifle from every guy you killed, unload it, and the drop it on the floor, that way you get insane amounts of ammo.