What I don't like are those sites with music.

Being a guy who doesn't get to play as often as I'd like, I put a lot of effort into trying to find ladies who might have some common interests with me. I usually go right to the "about me" page to see if we might be a good fit for a dinner date. Then there are the photos. I like a few candid shots, with a big smile. (If you show your face) Posed shots are okay, but what I don't care for are the ones that seem over-posed, where she's desparately trying for that sexy, seductive look, but in reality, she looks like she's in pain, and she probably is from all the posing. I also don't care much for music on a lady's site, too distracting.

My favorite site is Beverly Fisher's. I don't think anyone puts more effort into a website than Bev does. Take a look at her Slut Rants, very entertaining.

Yes they are important as I take great care in selecting a lady.

Plusses:
Lots of pics, preferrably not all pro-studio shots.
Accurate stats inc height and weight.
I too like dinner dates so mention them if you like them too and a little about yourself.

pet peeves:
Music aaaargh!!!!! please no
Complicated slde shows etc.

Glad you have an interest in our opinion.

Keep it simple and clear quick loading pictures that are not airbrushed. Details of services provided, of physical attributes, and interests if any.

Hell Yes!! Websites matter.  
What I like.  Recient and good pics.  If the lady wants to hide her face, OK.  But the rest needs to be clear. Easy to navigate.  Info easy to find.  Rates and contact info, e-mail/phone, should be given.  Availability should be clearly said.
What I hate.  Old/blurry bad pics.  Pics such that you wouldn't recognise the lady at the door.  Advertsing as 'busty', and showing nothing but butt pics.  No rates/contact info.  Calendar not updated.  If you are not going to update the calendar, don't have one.  Stupidly written ad copy.  Like, "Don't call/e-mail with any explicit rate/menu questions."  And she does not give this info, anywhere on the site.  The Worst:  Password protected pics.  Or haveing to regester to see pics.
Ladies' sites I like:  Jessie Yum Yum.  AngelinaDDD.
Agency sites I like:  MC.
Hope this helps.

I expect others like me find the lady's website important and likely a relection of the lady herself.
I look for recent, non-pro photos (within 6 mo)
Rates, calendar, personal stats.
I dislike music and having to "join" to see photos.  If you want to only allow some pics, fine, but to have to join or be a member to see you, not good.
Thanks for the opportunity to comment!

Yup. Nothing worse than photos that, when you click on them, are the same size as the thumbnail photo on the page. I don't need to count hairs, but please. Not only is it not helpful, but it speaks to my expectations of what an encounter might be like - not good.

Also, be sure to capture any special features which might attract some folks. I saw one photo, where I could just get a hint of some full lips (Venus, you go girl!) and that was all it took for me.