“The six brothers and sisters of the Bedwyn family are introduced in A Summer to Remember. Aidan’s story is told in Slightly Married, Rannulf’s in Slightly Wicked, Freyja’s in Slightly Scandalous, Morgan’s in Slightly Tempted, Alleyne’s in Slightly Sinful, and Wulfric’s in Slightly Dangerous. Characters from One Night for Love and A Summer to Remember appear in some of these books.” From Mary Balogh.com
Mary Balogh is the master at creating slightly imperfect heroines and heros. Of course, most of the men are handsome and courageous. But often, they are driven by forces from their upbringing, battling the demands of duty and honor.
The women are also brave and brassy. But usually, the women are flawed. Either low-born, “handsome” rather than beautiful, or full of deep, dark secrets from the past.
Villians play an important part in the Slightly series, as to mistaken first impressions. This leads to a whole lot of action and movement. She also is great with descriptive passages, helping the reader to envisage a place or person.
I wasn’t a big fan of all the books in the series, but as a dutiful and voracious reader read them all. If I had to pick, my two favorites were Slightly Wicked and Slightly Scandalous, mostly because they featured a lot of off-beat characters that you don’t always get in romance.
Regency Reader 
Slightly Scandalous was where I started the series and it remains my favourite of the ones I’ve read – Freya was just such an unconventional heroine and I loved seeing how the whole back story regarding poor Miss Martin was resolved in the Simply Quartet. Since you also preferred Slightly Wicked I will have to get it out of the library and finally give it a read. 🙂