Eh? Most of the stuff that's really exceptionally strong is in books. Occasional Dragon option hits an angle that nothing in any book does, but…
As an example, Flame Spiral, Demonskin Adept, +2/3/4 bonus damage to Fire feat, +1/3/5 Shard to implement, Staff of Expertise, Accurate Staff, Dual Implement Spellcaster, Arcane Admixture(to make Demonsoul Bolts fire), Robe of Eyes, and Hellfire Staff are all books. Yeah, Sarifal Feywarden is really strong with that, but if everything else doesn't blow up your game, Sarifal Feywarden is not the thing making your players go "you can do WHAT?"
Yeah, I have to agree with you. There's SOME stuff in Dragon which is really super good and formed the core of various tricks, like the White Lotus Riposte feat. OTOH there's a vast array of core book stuff which is foundational and awesome. I mean, really, just Rain of Steel, Rain of Blows, Twin Strike, Blinding Barrage, Come and Get It, Tide of Iron, these are often overlooked (and merely a small sample) of stuff which is incredibly good but rarely thought about because its simple core-book stuff that is all in PHB1! There are plenty of exceedingly good feats even in just that book alone too (and PHB2's feats are so stupid good that there isn't a character in existence that doesn't have a couple of them as major build elements).
I would say Dragon stuff is generally more peripheral and/or niche. There are things like the Spiked Chain technique feats and such that are pretty cool if you have a certain build, but only of passing note otherwise. A lot of stuff in Dragon was quite marginal, allowing you to create a certain flavor or something, but usually less absolutely effective than other options.
Still, Dragon is highly recommended. You might look to see if anything in it was later rehashed in a book though, as a good bit of it was, and usually in a better/tweaked form. There are also a few 'experiments', mainly in the last year or so of Dragon which are somewhat complex or may not be as workable as some of the other stuff. Rules covering hybridization of E-Classes for instance. They usually WORK, but I don't get the impression they got the kind of careful vetting that earlier stuff did. Even so I don't think there's anything there you cannot use.
Probably the 'least recommended' stuff in 4e would be some of the Essentials/Post Essentials material. HoS is widely panned, though I personally like a lot of the stuff in it. Still, its not fully usable without both Essentials and pre-Essentials material. HotFW and HotEC could be accused of the same thing, except neither of them has anything quite as much of a dud as the Binder, and they are both awesomely well-written supplements (especially HotFW, which could well be the best D&D book in existence). You certainly don't NEED any of this stuff, the classes and options it provides are pretty specialized stuff that only a few players will pick up on, but its still GREAT material! (and every GM needs to be cursed with a few Pixie PCs, so be warned).
