They didn't spend that much time animating the 5 hours story mode that comes with the games.
To be fair, Guilty Gear only has a handful of characters, and we'll never be able to compare budgets, but I imagine there was quite a bit more time dedicating to creating and perfect each model, compared to say... the horse which had all of 20 seconds of screen time.
That doesn't explain why the face on Gut's model looks terrible.
I'm guessing the studio and publisher was excited for the idea of carrying on what Studio 4'C did, but their ambitions were well above the what the talent pool could create, and those problems spilled over into every other shot.
I look at the part in episode three when Guts had his sword stuck in the rock, and how there was a series of shots with only extreme closeups, and I imagine a Shirobako moment behind the scenes where everything went very wrong, and the only solution to solve it in time for the air date was to make it an extreme closeup and hope the audience's imagination was enough to retain shot continuity.
With all the 3D elements, it really feels like an expensive show that looks cheap and horrible. If the japanese reception somehow doesn't have the same distaste as this thread and people actually buy the blu-ray, I'm guessing they'd learn from their mistakes and a second season would definitely have more 2D elements for the same amount of money.