I bought the Ghostbusters: Haunted Holidays TPB from Amazon for $12.14. It released a little later online than in comic shops. It was good to see some of the one-shots that came before "What in Samhain Just Happened?" and also ones I never read. I thought they were all decent 3/5 stories.
"Tainted Love" was my least favorite, mainly because the plot dictated them create a set of one-off equipment. Peter was surprisingly good in this one. It seemed like it'd be totally Winston-centric.
"Con-Volution" was surprisingly funny. The bits with Peter and the lawyer super-fans and the bit where Peter makes up those demon classifications were my favorites.
"Past, Present, and Future" had a nice twist with the Ghost of Christmas Present being the culprit and Peter again stealing the show, again, imo. I didn't care for how Winston was 'just an employee' line even though its a moot point. Anyone know what that 'Future' Gozer (or was it another Gozer Servitor) was based on?
The other reason I bought it was for the exclusive bonus 8 page story, "Guess What's Coming to Dinner?" by James Eatock (Cereal: Geek and commentator on The Real Ghostbusters Complete Collection) and Dan Schoening. It was a funny self-contained story about possessed turkey stuffing that really captured the voice of the characters from RGB rather than give us a standard zap, cap, and trap 'em/been there done that story.