I personally used the free url scan to…
In the beginning I only used the free URL checker to check some pages from my site, just to see is the tool good or not. The free scan is little limited, but the PDF report for the page was really useful for one quick check, and this was enough for me to decide and register for account.
After that I start using the scheduled scanner, so now the site is checked automatically and I don't need to remember to run it manual every time. This saved me a lot of time honestly. But the feature that I like the most is that you can scan trough a proxy and see how the site looks from other country. This helped me very much to check how the locale discovery is working, because is hard to catch these region problems if you don't see the site like a visitor from abroad.
So my opinion is, the free version is ok just to try, but the real value is in the scheduled scans and the proxy preview, especially if you care about accessibility in different countries. Recommend.