I would say rent it then go from there, me personally I'm a shooter/action/adventure fan over RPG centric games. In my own personal opinion I kinda of gave up on Final Fantasy along time ago, one of the reasons being a never ending series and that gave me the impression of it being overall less important and memorable to own. (unless they bring back my childhood Advent Children VII and VIII) I think *cough GOWIII>FFXIII cough* 10/10 GI mag (which is rare) cough * epic Triology cough *
1. Most of the games in the Final Fantasy series are different, even if its a "neverending series", its only a series by name, all the games have different plots/characters. Personally I think its more memorable because they are all single game stories.
2. You are comparing a Hack and Slash to an RPG... not a very good comparison.
3. You mention reviews... reviews are pointless these days. All the popular magazines and websites get some sort of revenue from publishers wether its actually being paid off, or having ads all over the site/magazine. Even if I could still take reviewers seriously, reviews are still just one persons opinion.
Disclaimer: Do not think I am a GoW hater, I love the games, I just wanted to point out some flaws with that post.
Anyway, as for your question Chesh. I can't say for certain if you should get it or not, especially since the only RPGs you have played are the Mass Effect series, which is alot different from other RPGs. I have played a few Western RPG's and enjoyed them. And like you, this is my first Final Fantasy game and my first JRPG too really. So far I'm enjoying it alot. Like True said, if you dont mind alot of cutscenes, a linear story etc, then at least check out some trailers, especially the gameplay trailers, the more I go through the game, the more I'm loving the combat.