First off, if you've read the first book - then you basically know the story. What's worse, you know more about the story than the narrator does. This makes for some interesting moments of dramatic irony, I suppose, and some tension (if you haven't read either, I don't want to give it away), but it's not that compelling.
Secondly, the narrator of home - Glory, Jack's sister - is far less interesting than the narrator of the first book. It's sad but true. Gilead is so incredible partly because it's narrator is so compelling; a preacher near the end of his life writing a letter to his young son, thinking about his past and wrestling with his faith. Not to mention, Ames has a beautiful narrative voice; incredibly rich language, gorgeous imagery - it's just lovely. Glory, on the other hand, is a middle aged spinster living with her father, mourning what she perceives as her somewhat wasted life, trying to confront and heal the wounds of the past created by her brother. The language she uses is not particularly wonderful. I suppose that's not her fault really, but it does make her less fun to hang out with. Also, writing the story from her perspective means we don't get most of the stuff that made the first book so interesting; the problems specific to Ames. While Glory's brother Jack was an interesting sideplot in the Gilead, he was a sideplot, and the main focus, Ames' own issues, were deservedly more central. Home gives you another perspective on Jack, which is interesting, but not enough to be central. Meanwhile, what ought to be the main focus, Glory's own problems, are pretty bland. In other words, what you lose from the first book is not amply compensated in the second.
Then, minor things - it kind of irritated me, for instance, that every so often there were accidental omniscient narrator moments. You can't write the book from Glory's perspective and then occasionally tell us what's going on in someone else's head. Sorry. You surrendered that right when you chose the first person voice.
Secondly, the plot itself, and Glory as a character in particular, just got old. Especially towards the end of the book, when it seemed like Glory was crying all the gdamn time. Either crying or cooking. Because I do have to admit, the descriptions of food were pretty mouthwatering.
Anyhow, overall, honestly, it's not a bad book, but I'd skip it. Read Gilead, and then read something else.