I loved Shadow Hearts II to pieces and put in about 50 hours or so (love those sidequests), so I picked up FTNW a while ago so I could continue along in the series. My understanding is that it's more of a standalone title with some recurring characters to SH/SHII than it is an actual sequel.
Qui-Gon Joe wrote:My recommendation: give it some time and then try it out. Then it might seem a bit fresher. If you don't, it'll probably be too noticeable that it wants to be its predecessor but doesn't quite make it.
I've tried playing FTNW several times in the past few months, but I just couldn't get into it. It's apparent that it's a little off-color like its predecessors, but it doesn't seem solid enough for me to plunk 40 hours into. Although, I would say that as an RPG it's better and has more potential than almost anything else that has been released in the past few years.
So, like Bernhardt said, why not check it out? You could like it a lot more than I do. I'd go with Joe's advice and wait a while, though. It's not going to be an easy transition from II to FTNW.