The single player is still awful and not much changed really.
Half-Life 2 is one of the very, very, VERY few games I'd ever give a 10/10. Honestly the game needs no explanation as to why it's a 10/10, if you've played it you know, if you haven't then go play it.
Yeah it's in my top 5 games ever, I like Portal and TF but Orange Box was all Half Life 2 for me.
GTA 4 was a truly amazing game, I pick it up today and the mechanics feel as good as pretty much any game you can buy. I constantly find myself forgetting that it's already 5 years old. My only qualm was the driving mechanics were a little off. I think that will be fixed for GTA V though, that's what makes me so excited for V, it's been 5 years since they made 4, they will have come along way since then.
EDIT: I was beaten to it!