To Yabia omer: Hacham Ovadia Yosef (1920-2013) was asked on different occasions about Hallel on Yom Ha’atzmaut. Hacham Ovadia writes that having Eretz Israel is not considered a miracle that is above nature like Hanukah was. Many soldiers had fallen during the establishment of the State and therefore it is not a revealed miracle. Hacham Ovadia continues writing that Eretz Israel today is a secular country and therefore many Orthodox Jews do not recite Halllel on this day.
(On the other hand, Israel is a scion for spirituality. It is filled with Yeshivot, Kolellim, synagogues and learning centers.
Therefore, if someone wants to recite Hallel on Yom Ha’atzmaut, he may do so without a beracha preferably at the end of Tefillah.)