www.mynewlongdomainname.tld
PRO
- easier to remember
- easier to type
CON
- not so good SEO-wise
www.my-new-long-domain-name.tld
PRO
- great, SEO-wise
CON
- who on earth cares to type so many hyphens?
- only way to get mileage out of it is if people clicked on it, reality is how many people would?
SOLUTION:
- buy both !!
- use the hyphenated domain as main url for SEO purpose
- use non hyphenated for those of us who will be trying to access your pages.
Best wishes and much success to you in your endeavors.