The 150 billion of unfrozen assets was given back to Iran in the sense that they were able to use the funds again.  The use of much of those funds was increased involvement in Syria backing Assad and Hezbollah and increasing their military.  

Like Trump or dislike Trump, many of us (and let's try to keep the personal insults down) believe that increasing the ability of terrorist supporting regimes is counter productive and creates horrible civil wars and refugee problems - like in Syria and Libya.

Which is why, I for one, support this action by Trump.

No, I am not a Trump supporter - no point in explaining why, most of us agree why .  

On the other hand, Obama was a weak foreign policy leader similar to Neville Chamberlain and his appeasement of Hitler prior to WW2.