The Alchemyst by Michael Scott: as tween I would have absolutely adored this fantasy novel about twins who discover they have magical powers, especially they way Scott throws in historical and mythological characters from all over the world. As an adult, I found the writing too simplistic. I'm not sure I will finish the series.
Everyone in my Family Has Killed Someone by Benjamin Stevenson: a meta-mystery that's a fun, modern take on the classic locked-room mystery, with a genre-savvy narrator who helpfully tells us which clues we can ignore and what pages the deaths happen on. I highly recommend it if you love mysteries and/or post-modern fiction.
Ten Thousand Stitches by Olivia Atwater: the second of her Regency Faerie Tales. This one was a riff on Cinderella, with a fairy godfather and a housemaid so angry at the injustices she and others experience she inspires the rest of the staff to engage in collective bargaining. Although I loved the idea that Effie's magic has the ability to stitch emotions into her mending and embroidery, I didn't enjoy this novel quite as much as the second one.
A Wizard's Guide to Defensive Baking by T. Kingfisher: this was an absolutely delightful story about a 14-year-old girl who uses her magical powers over bread to save her city, with the help of her two familiars -- a carnivorous sourdough starter named Bob and an adorably tough little gingerbread man.
The Oxford Murders by Guillermo Martínez: this is a re-read of a literary mystery set at Oxford and involving math (I love math!). It's very good, but I'd forgotten about the last set of deaths, which hit too close to home and leave a lingering misery in me. The movie version is not great.