See, here's a prime example of why "romance" is less a genre than an attitude: one could easily classify Heart of Steel and the preceding novel Brook set in this world, The Iron Duke, as sci-fi/fantasy, specifically steampunk/alternate history. (This is a universe where the Mongols had nanotech, and used it to stomp the heck out of their enemies (soon, subjects) for five hundred years.) They'd be marketed differently, of course, and there would be fewer abs on the covers (to stay with tired old stereotypes, you could just stick the heroines in leather on the front instead)--but I don't think the content would need to change a bit. Romantic plots and subplots abound in SF/F! Hell, even Perdido Street Station has a love story in it. Not that it ends well. (Boo, now I'm sad.) Wherein would lie the difference, I suppose--that all-important Happily Ever After.
That said, I liked Heart but didn't love it like I did Iron, not through any fall-off in writing quality, but just cause I wasn't as into the central couple, both of whom appeared in the previous book. Yasmeen is an airship captain--though she loses her Lady Corsair, and its crew, to assassins unknown early on here--with badass, acrobatic fighting skillz and slightly tufted ears, plus a murky past. I don't think she's any less of a Type than flinty policewoman Mina Wentworth was in the first installment, but I just didn't like her as much. Archimedes Fox is a treasure hunter and star of a series of pulp novels by his sister, Zenobia, last seen when Yasmeen abandoned him in zombie-infested Venice. (Oh yeah, did I mention mainland Europe is pretty much overrun with a zombie plague? That's pretty important.) Maybe I just can't forgive her for this? Though he certainly does, and I do love his soft, squishy romantic's heart, a great contrast with his swashbucklin' exterior. Together, they set off on an expedition searching for Leonardo da Vinci's clockwork army, dodging Horde soldiers and mysterious enemies all the while; along the way, trying deuced hard not to fall in love.
There's a lot going on here, and Brook does a swell job keeping all these balls in the air. She's clearly got this world more fleshed out in her mind than she will ever need to commit to print, and goodness, she knows her way around escalating sexual tension. More telling than all this verbiage? I will totes pick up the next in the Iron Seas series. Her website says late 2012.