I kinda missed most of the hex mapping craze during my early gaming career. I wasn't really introduced to it until I picked up the Wilderlands of High Fantasy box set put out by Necromancer Games a few years back. I'm kinda up in the air on my feelings about this style of map when used for a campaign setting.
1. I love just having a large bunch of encounters keyed to each hex. It is easy to organize, and very easy to look up information on the fly.
2. It gives the game a more sandbox feel, at least to me. Especially when the hexes are not set up where all the low-level adventures are in one corner, and all the high-level adventures are in the other corner. You could find a dragon one hex over from a small goblin cave.
2a. It makes it easier as far as just letting the characters wander wherever they want to, as there will be at least one interesting thing for them to find in any given direction. Now, if they can actually handle the encounter is another story.
1. Hexes are damn ugly. And they can hide map information if not done just right.
2. It makes it harder for me to picture how each kingdom or area is set up, and how they deal with their neighbors. The pertinent information is often in the various hex entries, which tend to be scattered about by hex number, instead of a separate country/area entry.
3. While it is cool to have big monsters living right next to little ones, an inexperienced or rash adventuring party could easily be killed just by heading east instead of north.