It's really hard to know what to expect as far as how it will play. Monk and samurai, for example, share gear but don't really share much else so far as gameplay style.

They also seem to still be developing the job and balancing it in with the rest, but we do know a little from interviews they've done. They've confirmed your ghost friend is not a pet, so it won't be like summoner in issuing commands to it. They stated that it will be similar to jobs like monk/ninja/samurai in that by doing your rotation, you'll be building up some sort of job resource that you'll burn up for other big attacks.

Also you can pretty much guarantee that the job will have positional requirements for certain skills considering that all four other melee DPS have to deal with that, though to what degree it will have them is up in the air. It could go anywhere from monk with every move having a positional requirement to ninja with only two moves having a requirement.

They have even said they haven't fully decided if it will be a more damage focused job like samurai or a more support focused job like dragoon. We'll really have to wait to see till the PR tour to know more.