The hate for FF13 is a lot more grounded in fact than the hate for DmC.
Full disclosure - I have beaten neither of the 2 games, and have only played the demo of DmC.
DmC hate, in a nutshell, is the following - I don't like how the new Dante looks, the game doesn't force you to use creative combos, and the combat system is clunky when you get to the highest levels of difficulty. Other stuff like the story sucks and the dialogue is weak is just filler - nobody ever takes that stuff seriously in fighting games anyway.
FF13 hate is much more real. The characters are stupid. The combat system consists of pressing "autobattle" over and over and over again. The game is a tunnel.
The DmC criticism indicate that the game is playable and solid, it's just not anywhere close to the perfect fighting game that the previous entries in the series. The FF13 criticism indicates that the game has committed the most serious no-nos that an RPG can ever commit. After all, what is an RPG without at least one of the following 3 elements - (1) a good combat system, (2) likeable characters, and (3) a cool world to explore. For critics of FF13, the game missed the mark completely on all 3 of those aspects.
I've played over a hundred RPG's in my life so far and I enjoyed Final Fantasy XIII; the hate is quite overblown. It has its flaws, yes, but it's really good.
Also lol @ people trying to convince others that it's the "worst RPG on the market." What a joke. I mean, I don't approve of the Lightning Saga myself, but man, some FF fans seem like jaded, whiny losers. Here's the truth :
83% average on Metacritic from critics, an 80% average from over 1,500 reviews
A whopping 49% average, despite being a mainline title, proving that critics won't just award a Final Fantasy game with a high score even if it's equivalent to crap in a box in terms of quality.
I also included user input to show that it's not just the critics. You also can't say "it's the lowest-rated main FF" as it's shown to be higher than FFXI, FFXIV, FFV, FFT, FFIIIDS (the only internationally-released version of the game), and FF Origins (first international release of FFII), and the highest rated FF in the series, FFIII, has a 93% average on Gamerankings from just 11 reviews, whilst FFXIII has an 85% from 60 reviews.
So, yes, Final Fantasy XIII definitely has its flaws, but it also may just not be your cup of tea. It does not mean that it's the "worst RPG on the market."
"Dyin' is easy. It's the livin' that's hard..." Grim Reaper, Maximo vs. The Army of Zin