For starters, I'm most certainly reading Mira Grant's work out of order. I just recently completed Into the Drowning Deep, the review of which you can find here. I adored it and wanted to read more by her, so went out and grabbed the Newsflesh trilogy.
I absolutely loved this concept, but I did not get into it the way I got into Drowning Deep, though they're totally different ideas and cannot be compared.
Feed takes place 25 years after a Zombie outbreak. Everyone is infected and will turn eventually, but society has learned to live with it. It's a day and age where the most trusted journalists are bloggers, and we're following a couple of them from a site selected to get exclusive access to the latest presidential campaign.
This is not your typical zombie horror book and you'll be disappointed if you go into it with that expectation. What Mira Grant has done here is imagined, in a very realistic way, what the world would like like decades after an outbreak and how humanity would cope with it. There's a tremendous amount of world building that's done incredibly well and the technologies she's imagined are just advanced enough and subtle enough to feel entirely plausible and believable.
While the writing is impeccable, I had just recently read some of her latest work and could tell that her writing, and dialogue especially, had grown a lot since Feed. I also had some problems with the narration of the first 90% of the book that would give major spoilers away if I said any more, but it was otherwise a lot of fun with some really cool characters. I honestly had a blast reading it.