Hiya!
Art. As I always say... it's nutty.
I chose "Very Important". But that's in regards to MY preference for art, obviously. So "Very Important", then I see a book and flip through it, and say "Man, this is cool looking. It's got a nice feel to it..." ...and then the guy next to me says "What?! Really? You're kidding right? You're not? How in the heckfire can you like this? It's mostly words, no background for the pages, and absolutely zero colour art! None. Just all black and white sketches of random items, locations, and...look at this. It's a picture of a couple rats, I guess, around the base of a couple barrels with a sack of grain pouring out on top and onto the ground. Boring and pointless".
Then they hand me a book and I open it. Glossy pages, every page has a fancy marble/stone backdrop, fancy layout with filigreed "box text" on almost every page, and half-page "portraits" of the same 5 heroes, striking a pose as if they were doing a photoshoot...all with very little to no actual 'setting' for that pose (kinda just floating on the page with a vague outline of ground/cobblestone/flagstone/wood at their feet. "This is a beautiful book! Look at the art. It's ALL full colour on high quality paper, with a consistent art direction and recognizable characters throughout". ... ... To which I then reply "Uh...naaah. Not my thing. Colourful, sure, but...boring. It's repetitive and predictable, with no sense of wonder. It has no 'feel' unique to itself. It 'feels' like every other game put out in the last 20 years that all keep trying to do the same 'quality'. Ick".
So...yeah. "Very Important"; if I see non-glossy pages, no fancy background 'texture' for every page, simplistic boxed text, and each piece of art has me asking a question immediately... sign me up! But give me, for example, the 5e PHB or pretty much ANYTHING put out by Paizo...and my eyes glaze over and the feeling of "Oh..yeah...been there, seen that... blaaah..."
For me: Colour pic on the cover of the box (or books), b/w non-glossy paper throughout, and primarily "a random variety of b/w/greyscale sketches of interesting things, locations, critters, NPC's, etc", and I'm ALL IN!
Example:
Bad: Anything by Paizo, really.
Good: 1st edition box set of Astonishing Swordsmen & Sorerers of Hyperborea
^_^
Paul L. Ming