Nightfall said:
My best reasons I gave but I have more.
1. Different monsters. Things like the Dark Hag, the Danashee, an a sortment of hags, and creatures of Mormos brood like the Aassthi and the High Gorgons. Also the Feral, Blade Demons, the Unhallowed, and DEFINATELY the Slitheren/Ratmen. These guys are numerous, they fight well in groups and they also can make interesting PCs!
Is that the best ya got
I used a spined lizard just last night in my Kalamar game! The creature collection books are great - but one can use the monsters (most of em) in any campaign world. Hookwings are also going to soon be showing up.
Nightfall said:
2. Paladins and clerics aren't treated just as healers and do gooders. Some paladins might follow Madriel, or Hedrada, but most follow Corean since he IS the god of paladins (which is an important thing not like Torm whose just a lesser god. ). Even so, they can work together
The religions of the Kalamar campaign are far superior to the religions of the Scarred Lands campaign.
And each religion has far reaching inplications on the career of any adventuring cleric that might want to belong to that particular cleric. Want to be a Paladin or Cleric in service to the God of bravery? You aren't allowed to use ranged weapons of any sort. Want to be a druid or cleric in service to the goddess of nature? You must pick one of four elements to serve. Want to be a cleric int he home foundation? You must care for orphans, defend the homeland and preach the strengths of marriage. Want an evil cleric? The plague bringers are all infected with deadly diseases and must fanatically make converts or die from their disease. The clerics of the overlord must promote slavery. The clerics of the Prince of Terror must try to promote deadly fear in those around them, using drugs, magic or whatever is available. No cleric, played right, is going to be a carbon copy of another cleric from another religion.
Nightfall said:
3. The Horsemen of Vangal! Best damn horsemen out there and they know it. I mean come on Dual wielding battle axe god of destruction, earthquakes, volcanos, bloodlust and LOTS of meaty death! Trust me Talos would choke at Vangal's power.
You got me on the horsemen

They are pretty cool.
Nightfall said:
4. It will be something your players might like. After all they can still right wrongs, do good deeds, find wealth and treasure from times long past...just as long as they are careful. Not to mention if one or two have a pentence for arcane learning, there are a number of places they can try. From the halls of Hollowfaust, to the Vault in Lokil, to the Phyaltric Vault in Darakeene, there is plenty of arcane lore to be learned.
Kalamar has Giilia, city of the bats, a city ruled over by a vampiress and built atop an endless maze of ghoul tunnels. It has Thygasha, a city in which two warring temples, one promoting peaceful sleep, the other promoting nightmares, war over the sleep/dream inducing drug, Silver Sand. Nearby is a desert, uncharted but filled with lost cities and mysterios lore. buried deep in the Vohven jungle is the original temple of the Founder, a temple built by the god himself and doubtlessly the home of many secrets.
Then when one is tired of hunting for buried arcane secrets one can travel to Kalamar and become involved in the depths of the great political intrigue or perhaps journey to the city of spies and try to make a living there. Kalamar has it all
Nightfall said:
5. TRUE RITUALS!! I know you read R&R, but THINK about the awe you could inspire with your players IF a cabal of wizards cast Lycanthropic plague. Or perhaps one is searching for a quick way to lichdom?
And like the monsters, why can't one import true rituals to other worlds?
Nightfall said:
6. Read Lars's Story Hour.
Lars Frehse has his own story hour about the Scarred Lands. I'll post the link here: http://enworld.cyberstreet.com/showthread.php?s=&threadid=12803
I think it's one of the better ones out there. Anyway hope that semi-helpful on that point.
Or you can read my Storyhour
Servants of the Swift Sword, which I plan on updating today. Its just in its early stages but I forsee great things for it (provided the players don't get killed)
Nightfall said:
7. Running the Scarred Lands will be challenging. There's really no epic NPCs, no epic dragons, or even just epic creatures beyond those that serve the Titans or perhaps forces outside Scarn. Even so, it's a fun thing to see your players try to figure out just WHERE everything fits.
Ditto for Kalamar
Nightfall said:
I don't know if I can add much else other than RUN PLEASE!
I need to fill my conversion quota for the month.
Aha! The true motive is shown at last. He has a quota. Of souls no doubt. Don't fall for it! Turn before it is too late. Take a look at Kalamar! 
Seriously though, the Kalamar setting book is very non specific in what edition (or even what set of rules) one must have to use it. One could likely use Harnmaster, 1e or 3e equally well with it. The Players guide and the modules are more geared to 3e but even they could be pretty easily converted.