I've read S+F, DotF, S+S, T+B, and MotW, and disliked all of them. I found roughly 2 pages of useful material in each -- and that's not enough to warrant buying them. (I liked about 5% of the feats and 2 or 3 of the PrCs, total.) That's all opinion, and everyone can disagree.
I was severely disappointed with Sword and Fist, and will only consider buying another WotC splat after someone else has purchased it and let me read it. If it's a good product, then sure, I'll buy it. I'm not against WotC products or their business, but I feel I've been burned with some of their low-quality garbage, so I will look before I leap.
The way I see, WotC has the marketing advantage of their logo and the title "official". To compete, other companies have to offer something else, such as "higher-quality", a cool setting, uber-powerful stuff (marketing to munchkins), innovation, doing something that WotC doesn't do, etc. Some companies have used one or more of these strategies and done well. I feel that WotC sometimes relies too much on their logo and title -- those are assets that can be expended.
What I'd really like to see is guidelines for creating PrCs and, possibly, feats that are specific to campaigns. It sounds and feels like a powergame nightmare, remembering Skills and Powers, but someone needs to do it, and it sounds like it needs to be a WotC product. But that's another thread...
OfficeRonin