Very nice site and easy to navigate. I think you may have paid a little to much, but I don't know all that you got for your money.

From SEO standpoint it seems that your are trying to promote:
O.C. Real Estate Advisors
Orange County Real Estate

The 1st appears twice only - no real mention of keywords in the body content.
Orange County Real Estate in headings but not text content.

Design: clean professional design

The real answer is... Only you can answer whether or not your $20k was worth it. Any other advice given here is pure speculation, technical, or irrelevant to your question to begin with.

My personal opinion - No not at all worth $20k. Sales people love to be sold and you were sold. Nothing wrong with that as long as you are satisfied with the end result. So...

Since we do not know what goals you and your developer established before the site was created and whether or not those goals have been achieved. Was it SEO for keywords? Was it corporate branding? Was it newsletter signups? Was it strictly ROI based on your different verticals?

I am sure you had goals in mind and and am also sure you are measuring the performance of the site to those goals. If your goals are being met, job well done and well worth it.

Do not get me wrong, specific functionality not working and listings not being found and other site issues are a definite signs of value, which is at the heart of your question, but I have seen some crap sites earn huge money so it is certainly not the deciding factor.

$20K? OUCH!

There is no website worth 20k in my opinion. That 20k hopefully includes extensive SEO work

I like your site, very clean and intuitive to use. I am not a techie, so I cant speculate as to how well it does for SEO and if a big part of your investment was made towards SEO/SERPs. But I can see how you could have a high capture rate from your site as it is very user-friendly.