Ok, I only got to rank 10 on Marauder because I was trying to level every class in the beta just to see what they are all like. Right now, as expected, Marauder is still my favorite job. I'm going to give a quick synopsis of the first 10 ranks to hopefully help people get a better understanding of the class.
First I'll go over the abilities quick:
Light Swing 1- Basic attack. I've noticed that on a critical, you seem to swing twice. I believe you can also double attack normally, as I've had a bunch of times where I didn't crit but still swung twice.
Broad Swing 1- This is basically the AoE version of Light Swing. If there are more than 1 enemy around you, just spam this instead. It seems to miss slightly more than Light Swing, but does equal to slightly higher damage on average.
Bloodbath 6- God I love this ability. It makes your next attack heal you for a certain percentage of the damage dealt. It seems like a fairly decent percentage too, as I usually recover anywhere from 100-200 when combined with a Trunksplitter or Skull Sunder. I'd also like to point out that this skill should come in EXTREMELY useful when combined with Lancer's Ferocity (consume HP to increase attack power) or Archer's Raging Strike (increases attack power, but I'm not positive if it translates to other classes).
Now for the Weapon Skills:
Trunksplitter 2- A great starting WS. It is quite powerful, usually dealing anywhere from 150-250 damage and has pretty decent accuracy. As per ffxi, acc seems to be based off of what mobs you are fighting.
Brandish 4- The first AoE WS. Tbh, I didn't use this very often, mainly because I didn't have the ability points to equip it (I tried to keep 2 cures available for soloing). The times I did use it, it worked quite well against groups. It did around 150 damage to each enemy.
Skull Sunder 8- This is my favorite WS. First off, it only costs 500 tp instead of 1000. Second, it hits HARD. I often found that my skull sunder would hit as hard or harder than Trunksplitter. Third, if you enter steadfast stance (don't move for about 5-10s), it becomes an AoE WS. This is beastly for guildleves with groups of mobs. You can get close, draw your weapon, attack a few times til you get the steadfast message, then use bloodbath > skull sunder. You will ANNIHILATE things.
Defender 10 A useful "Oh sh*t" move. It definitely does mitigate the damage you take, however for a DD class it is somewhat lacking (just like ffxi). I see this as more of an ability to take for your gladiator, or if you are building a hybrid tank on your marauder and stealing skills from glad.
So far, the only downside I've found to Marauder is that they aren't QUITE as survivable as a class like conjurer (which is a solo MACHINE). At level 10, I still had a very difficult time against Dodo's, whereas my rank 8 conjurer was taking down the easier ones.
Overall though, the class plays really great and I can already tell that it is going to be a POWERHOUSE damage dealer. Please feel free to comment or add your own thoughts about the class. Once open beta starts I will probably not play marauder again as I want to save it for release, but knowing the potential is there, I believe it will make a fantastic class at all levels.