I read the first volume, the whole chrysalis arc thing.
I enjoyed it, but it was a little darker than I was used to in terms of "official" pony; plus- and I know this opinion is an unpopular one- but I'm not a fan of the art style. The pages look cluttered and the ponies look like their eyes are going to pop right out of their skulls! It's just very un-cute to me
The nightmare rarity arc sounds like a trainwreck, but I'm sure it's not as bad as Nerdy!Shining Armor trying to get Popular!Cadence to date him. I never thought I'd say this but I prefer fanworks to that garbage >_> But hey, maybe it's not as bad as I'm thinking it is. (I kinda doubt my opinion would change though)
I'm sure the Big Mac stuff turned out okay, but I'm a little biased since I like big mac