On the whole, it's pretty much a safe bet that just about any anthology collection is bound to be hit or miss: some stories will hit all the marks, while others will be, at best, 'meh'.
Silent Nights is one of the rare ones where even the weaker stories are better than average. I reviewed the first 4 here, but here are my thoughts concerning the remaining stories.
Stuffing by Edgar Wallace - ★★★ There was a definite The Blue Carbuncle vibe to this story. It was short, and amusing, and was amongst the stories in this book with the most Christmas spirit. It was short and told in third person so even though I really enjoyed it, it was hard to rate it higher.
The Unknown Murderer by H.C. Bailey - ★★★1/2 This one was just plain weird, but oddly satisfying. Twisted story / mystery, but the ending was unsatisfactory. I wanted more information.
The Absconding Treasurer by J. Jefferson Farjeon - ★★★ I'm not sure I'm destined to be a Farjeon fan. This is the second story I've read by him and I'm left feeling short changed. I liked the writing, but the mystery was really non-existent. The investigator doesn't share his thoughts with the reader - or the clues - so you're with him for almost the entire story, and then suddenly he goes for a walk, finds a body and voila! knows the solution to the entire mystery. The writing saves this from a 2 star story though.
The Necklace of Pearls by Dorothy L. Sayers - ★★★★ I'm a fan of Whimsey, so even though Sayers pulls something of a Farjeon in this short story, I find I didn't mind quite as much. Even though I don't think the reader gets enough information to solve the mystery, we do at least get all the elements, making it easy to see where Whimsey is going. And the crime's concealment was freaking ingenious.
The Case is Altered by Marjory Allingham - ★★★ The fact that I had to look this one up again because I remembered nothing about it probably says more than I can for the story. It's not bad, nor badly written, it just wasn't memorable.
Waxworks by Ethel Lina White - ★★★★★ I was sure I was going to dislike this one when I read the author intro, where Edwards highlights the author's focus on writing suspense stories. But oh man this one was so good! Even though I knew how it was going to turn out - really, everything about the first part of the story made the ending inevitable - I had no idea how that ending was going to happen. I was expecting something far less subtle than I got, and that subtlety, and the twisty bit, was what made the story so good.
Cambric Tea by Marjorie Bowen - ★★★ This story started out promising to be another 5 star, but in a gothic vain, but lost steam at the very end, with a disappointingly weak ending that felt the result of the author writing herself into a corner and then copping out.
The Chinese Apple by Joseph Shearing - ★★★ Oddly enough, as this is written by the same author as Cambric Tea under a pseudonym, this story's problem was the exact opposite of Cambric Tea's: weak build up and a solid ending. What is supposed to be the plot twist was obvious to me from the start; but the ending was so satisfying it scored extra points from me.
A Problem in White by Nicholas Blake - ★★★★1/2 An Encyclopaedia Brown type of mystery! I had a very hard time at the start figuring out the characters - the author gave them all nicknames, then two pages in gave them their proper names, confusing me to no end. But Blake gives the reader all the clues and then doesn't give the solution - it's at the back of the book, allowing readers to try to guess whodunnit without being influenced. (I haven't had a guess yet, because I need to re-read it again now that I have a better idea of who is who.)
The Name on the Window by Edmund Crispin - ★★★★ I really enjoyed the writing in this one an awful lot, which made the abrupt ending to the 'locked room' mystery easier to put up with. I'll definitely be reading more Crispin.
Beef for Christmas by Leo Bruce - ★★★★1/2 I've read Bruce's other series involving the Professor and I like him as a main character better, but Beef's a very clever man and the writing was top notch. The reader doesn't get all the facts, but the story compensates; this one felt far more complete than a lot of short stories often do.