There was a noteable lack of inclusion of several races from the PHB (specifically Tieflings, Dragonborn, Gnomes, Half-Elves, & Half-Orcs) but they added 6 new options, plus new subraces. All the races got a bump in ability (except the Humans for some reason) so if you're going to add back in any race, you'll want to give them a similar boost. There are new options for all the classes (except Ranger) and the re-inclusion of prestige classes that have high restrictions for "multiclassing" into, to the point where they would have been better as class options. There are new half/partial backgrounds where you take one social and one regional option to form your background. New feats, equipment, spells, magic items, etc are all available too. I haven't made a thorough enough read through all these to comment in detail, but there looks to be a lot of neat content. I will say there are some new Cantrips which are really nice, with the exception of Enumerate, which lets you know exactly how many there are of something. Kinda lame, IMHO. Flich and Instant Wardrobe are fun though and would make excellent additions to an Arcane Trickster's repertoire. Near the back there is a gazetteer, of course, and a whole chapter devoted orginizations, handily split up by Arcane, Criminal, Death, Devotional, Mercantile, Military, and Political categories. Wrapping up the book is a collection of titanspawn monsters, including many of my favorites from the old Creature Collections and notably has stat blocks for both Asaathi and Slitherin (snake & rat people that have now been given as PC racial options). It lacks an index at the back, but the very detailed Table of Contents at the beginning makes up for this.
While I do feel something was lacking to really hook me into the setting, over all it's a pretty good book. I'm not sure how new players to the Scarred Lands will appreciate this edition, but as a fan from the original release, I'm quite happy and excited to kick off a new campaign to explore Scarn.