The phrase "we fully appreciate" is correct and usable in written English.
You can use this phrase when you want to express that you fully understand and value something. For example, "We fully appreciate the hard work you have put into this project."
Only when we reached the top did we fully appreciate the monumental achievement - or folly.
I don't believe we fully appreciate the challenges that lie ahead".
How often do we fully appreciate, for example, how hard our hearts work day and night to keep us alive?
We fully appreciate how frustrating this is, particularly to users as engaged as our iPhone audience are.
We fully appreciate the need for New York City and its vital institutions to grow and prosper.
"I do not think we fully appreciate how devastating Anaconda was," Brigadier Lane said, as he emerged from a Chinook helicopter.
In our case, although the relationship began in 2008, it was not until after the pre-trial work was in its final stages (in 2013) that we fully appreciated the extent to which Canadian team members and South African researchers had different expectations and priorities within this complex multi-component intervention.
"We know we have to digest this first, before we can fully appreciate it," their coach Ralf Rangnick said after the match.
In other words, when we cannot appreciate the love of another we cannot fully appreciate its power within our own experiences and vice versa.
We have diverse interests here at The Creators Project, which is why we can fully appreciate the awesomeness of Jimmy Fallon's unexpected Saved by the Bell reunion last night.
From 2011 we can fully appreciate the irony.
