There are now two different realms, and the creator has mentioned the possibility of hardcore and casual realms someday. Here is my opinion:
Casual realms must be done cautiously. The reason open PvP makes an interesting world is that you have a lot of different characters in the same place. Some are really bad dudes, other people are just there to get XP, occasional saints, roleplayers, backstabbers, noobs, people who specialize in strange magic, and maybe someday people doing tradeskills like chopping wood or picking berries.
If you make an area or realm which doesn't allow PvP, or is for some other reason much easier with no drawback, then you get these various people being split up. The PvP world will be purely for people wanting to attack eachother, because any other player will train in the safe world. This ruins it for everyone, since people who want to experience a proper open-pvp world (with a mixture of character types) still end up training in the safe world, because the PvP world no longer contains a mixture of good and bad characters, since bad and good are no longer forced to be together. It becomes a giant game of Prisoner's Dilemma, where it is in everyone's interest to defect even though it would be in the group interest to co-operate (in this case, to play in the same world).
That said I still think casual areas or casual realms are not to be dismissed. They just need drawbacks. Perhaps weak loot for instance, or less experience, or bosses blocked off. That way you still get lots of different types of people in the dangerous areas, because they have an incentive to go there and try to survive.
In general, realms are really cool from a creative perspective. There could be heaven and hell realms, weird realms, realms that are really complicated or difficult to get to (such as for powerful mages), realms where everyone has large heads or mustaches. Possibilities are endless, and minor changes in color or design will still feel like exploring somewhere new. So overall it is a lot more fun then just choosing "server 1" or "server 2", and like many updates I am very impressed by the unique approach to an old problem.