Based on definitions from Linguee and de.wiktionary.org, both "schätzen" and "zu schätzen wissen" seem to be used to mean "to appreciate".
Examples from Linguee:

1. Kunden schätzen guten Service und Zuverlässigkeit.
2. Ich weiß deinen Rat zu schätzen.
3. Der Chef weiß meinen Einsatz zu schätzen.

My guess is that "zu schätzen wissen" implies that someone has experience in the consequences of not appreciating advice, commitment etc in the past, and now know to appreciate it.

I would like to know when "zu schätzen wissen" is more appropriate than "schätzen".