By which I mean would I understand this game having not played any Disgaea game before? (besides a brief few games of Prinny)

Yes and no, with a bigger tendency to no.

The Disgaea franchise features an extremely complex gameplay.

You can play through the main story without any struggles and enjoy it, but what the game really is about is the post-game content, and that is huge. I think new players will find themselves a bit lost between all the features and possibilities.

If you're new to the franchise, you should familiarize youself with a few keywords first, such as magichange, item world, staticians, reincarnation, homeroom clubs, reverse pirating, etc.

I suggest you spend a few hours here: http://disgaea.wikia.com/wiki/Disgaea_Wiki

So you know what you can expect from the game.

I played Disgaea 3, Dark Hero Days, Disgaea 4 and now Absence of Detention, and still haven't used all the content the games have to offer. It's no exaggeration if you say you can spend thousands of hours with Disgaea.

That being said, it is also possible to ignore the post-game and simply enjoy the main story. Have fun either way! :)

Started playing Absence of Detention and I havent played any Disgaea before. Story wise you should be fine and the more complicated systems arent necessarily integral to the main game.

Like Morrow pointed out theres a ton of stuff that might seem intimidating at first. I unlocked Item worlds, checked out the tutorial (which is really good by the way) and proceeded to completely ignore it for now atleast.

If you are a fan of JRPs and particularly the tactical kind, you should definitely check it out. Queuing up your attacks and making sick combos instead of using abilities and skills one by one is a great departure from the usual turn based gameplay.

I've been wanting to get into Disgaea lately as well. I always try really hard to like SRPGs, but I'm so bad at strategy games (as I have no strategy skills - I've never actually won a game of chess, for instance) that it's kind of hard to find a series that I can enjoy without eventually hitting a vertical wall in the level of difficulty.

You can easily finish the 40-60 hour story without looking up anything or playing the last games.

Doing anything post game and hitting level 9999 on the other hand is a different story.

Alright thanks for all the feedback guys, definitely gonna pick this up as soon as I can then :D need something to really sink my teeth in to on the Vita so 40- 60 hours minimum sounds pretty good!

The best way to become familiar with the game and it's intricacies is to just play it.  I had absolutely no idea what the heck this game was when I started playing 3 back on the PS3.  A couple years later it's one of my favorite series.  The item world and reincarnation will be crazy complicated at first but eventually it becomes second nature.  Plus, the internet is a huge help.