I had lots of fun with Charlotte E. English's Draykon, book one of her Draykon trilogy. (I've read book 2 too, which is just as good, but it's not free so I'm not reviewing it.)
So I really like the setting. It's an 18th-century/steampunky sort of place, with lots of magic. People live in the Middle World, between the Upper and Lower Worlds, and some people can make gates to one or the other of those. That's uninspiring, until a couple more details show up: the ever-lit Upper and the ever-dark Lower worlds are just wild lands, not Heaven and Hell or anything close. 3/7 of the Middle World has aligned itself with the Upper World, and 3/7 with the Lower -- which is to say, they have adopted plants and animals from the respective world as the basis of their economy. The lands aligned with the Uppers are in constant daylight, those with the Lowers in constant night -- and it takes the sorcerers of those countries a ton of work to maintain the appropriate illumination.
And the flora, fauna, and inhabitants are just as ingenious and interesting. I love the glissenwol trees, which are sort of giant mushroom/pines. And some of the people just happen to have wings, which nobody finds remarkable, though just why is a plot point in book 2.
Good characters, too. The book is about (1) a very shy jeweler named Llandry who discovers a supply of a mysterious gemstone, and (2) a stylish and powerful summoner and official named Lady Eva Glostrum, and (3) a cast of thousands. The main characters are strong, distinctive personalities, likeable and interestingly flawed. Sometimes even the characters' strong points come and bite them in interesting ways: Eva has many admirers and lovers, but that does not always work in her favor.
The names ... oh, the names. I appreciate the art of coming up with good names, and the author has come up with a zillion of them. Unfortunately they're mostly two-syllable names with similar rhythm that seem to come from the same language (and many of them do come from the same language or at least the same country). Individually they're often delightful. En masse they kind of blur together. The trilogy has lots of characters who live their own lives and show up in the story occasionally, and it's hard to keep them straight. (And why did she have to call her dragons Draykons? They're unambiguously dragons.)
There's a lot of mystery in book 1. A significant portion of it has been cleared up by the end of book 2, and a significant portion of disaster acquired in its place. I'm looking forward to reading book 3, which is already on my Kindle.
Rating: five mysterious gemstones out of five: top 20% of books I expect to read in a year.