I would place Scarred Lands squarely in the "Moderate Magic" category -- assuming that you consider the guidelines set forth in 3e "moderate". More than any other setting, Scarred Lands is a D&D, rather than d20, setting -- all the races, classes, toys, and tricks are there in full force. The way the setting is designed I tend to liken to Greyhawk more than the Forgotten Realms; that is, there are lots of baddies in Scarred lands, and not so many Drizzt's and Elminsters. this is a good thing, i think, as it underscores the importance of the PCs as the heroes.
On a side note, i suggest you pick up more than just the Gazzeteer. At least get the CC and R&R, and if you have any desire to use the gods and titans to their full advantage, get Divine and Defeated as well. The game screen is useful (although it is folded wrong!) in that it includes Scarred Lands specific racial rules and a couple of solid low-mid level adventures. I don't have any of the city supplements yet, and I have yet to buy Vigil Watch (which looks damn fine) but the Wise and the Wicked (NPC book) is lots of fun, particularly for giving you a flavor for the setting through its characters (plus it has stats for some of the truly epic bad guys of the Scarred Lands).
The theme that seems to run through all Scarred Lands products, it seems to me, is that PCs are meant tostruggle against great odds and reap great rewards for doing so. The enemies are powerful, often very much so, but relics, true rituals, and powerful prestige classes are presented to balance this. It seems like it works well enough for both hack-n-slash style games and more storytelling (but still action oriented) campaigns.