。
The state of education in this world is just disappointing.
Literal
This world [genitive-の] education [target-に] [contrastive-は] disappointed-do-end-up [emphatic-てしまう].
がっかりする ('to be disappointed') is built from the mimetic がっかり, depicting the slumping feeling of letdown. The auxiliary ~てしまう adds a nuance of resignation or unintendedness — 'I just end up disappointed,' as if one can't help it. The combined particles には mark 教育 as the target of the disappointment (に) while contrastive は implies 'this world's education in particular.'