I've never seen anything of Saiyuki save fanart, so I'm not going to be able to make any little character-quips this time...but going on the picture alone, I definitely agree that this is one of your best. When I first clicked on it I was all "No, this has to be a copy of a manga scan, or something!" before I recognized your style ^_^;
My favorite is the...um...guy on the far left. (Sanzo?) Profiles are evil evil EVIL things, and his came out very well, as did his body positioning. His hair also looks especially nice. And all of their hair does look very soft.
The...standing middle guy's arm looks a little awkward, but I think it may just be his thumb...it sort of looks like it's not completely attached to his hand, or that it's a little too long (...am I making sense?)
I don't think I'd color this one...the black and white has a nice feel to it. It might be helpful to darken it up a little in PSP, but it's not necessary. Oh! If you did want to add a little color without actually coloring the picture, you can tint the lines another color in PSP...or add a sepia effect, which would preserve the nice black and white effect, but make it look something like an old-fashioned photo is fond of the sepia effect
...one question, though: Are they on a hill? XD
I still stand by my saying that this has to be your best work ever. XP Very realistic indeed. And DO NOT COLOR THIS! Seriously, it's awesome the way it is. Especially with all the detail.
Gojyo definitely did turn out the best. Though he looks a little younger than in the volume, but I really love it. >3 His hair turned out the best as well. So limp and life like. And his eyes are great. His hands look a lot more realistic than what you usually do. ^^ But the thumb could probably be a tad smaller. It'd also be best if maybe you could try to be a little more subtle on the muscle marks on the arms, though this was an improvement.
Sanzo's profile turned out pretty well actually. ^^ They're a pain. His scroll though could use some markings around it though. XD; I've noticed though in the manga that Sanzo profile always turns out a little odd.
Hakkai's face could've maybe been a little longer, but I love his hair and outfit. The spots on his sleeves where they meet their armbands are particularly kewl. All the different curves and whatnot.
Goku looks good too, the outfit is exceptional. >3 And yay! The blood looks a lot better than usual. XD Very . . . oozing.
Now you just need to learn how to shade. >3 'cause black and white images can have just as much life as colored ones. ^^