Here is an example of a prestige class to give you an idea of what to expect.
Storm Sentry, a prestige class by House Lyrandar (Mark of Storm)
A 5 level prestige class easily taken by lightly armored fighters, swashbucklers, scouts, etc, the Storm Sentry prestige class emphasizes House Lyrandar’s abilities with wind and rain to increase their combat abilities. D10 hit dice, fighter BAB, Good/Good/Bad saves, 4 skill points per level, and some good mobility skills (balance, escape artist, climb, tumble, etc) make this class pretty decent just from the stats before even describing the special abilities.
A Storm Sentry can use their Gust of Wind dragonmark ability more times per day than normal, as well as exchange uses of their Dragonmark for featherfall as a free action. Higher levels gives the Storm Sentry the ability to exchange more uses for additional powers such as casting shield, doing a ranged bull’s rush (think a focused wind blast), give the shocking weapon ability to your weapons, and finally your gust of wind gets replaced with Gale force; knocking down medium creatures and literally causing small creatures to be sent flying!
I think the Storm Sentry is different, especially for warrior types, and really emphasizes that House Lyrandar is master of storms.
The last few pages of the book focus on feats and magical items. The feats are pretty cool, and necessary if you want to make a dragonmarked character that doesn’t feel like you had to sacrifice too much just for the “theme” of your character. One aspect I liked is that the Aberrant dragonmarks were expanded upon! I don’t know about everyone else, but when I read about the War of the Mark and compared the description to the aberrant mark in the EbCS, I was disappointed. Well with this book, aberrants are fully fleshed out, with lesser and greater aberrant dragonmark feats! There are also additional feats making dragonmarked characters simply “better” than other people, they are “living” representations of the Draconic Prophecy after all.
The magic items are interesting, for the most part they expand off of some of the dragonshard items in the EbCS that allowed a dragonmarked character to use their ability more times per day or use their abilities in new ways.
I really have liked the book, and hope others out there will too. For players, I think many people will want to make a character and try to participate in some of the great intrigue the book describes between the houses. For DMs, I think you won’t be able to help but to come up with half a dozen adventures after just skimming through. Heck, I feel like shackling people down every day of the week just to go through some of the adventures I’ve been cooking up!
The book retails for 29.95, but is available right now for $19.77 on Amazon.com, if you play Eberron it’s a must have! If you play a homebrew campaign, you might want to skim through it, see if the idea of introducing a dragonmarked house as a major economic power might appeal to you.