Yes, the in store upgrades are always free.
Upgrades are kinda a risk thing. Sometimes they work great and you come out with a phone that is 3 times as good as the first version! Sometimes, they can add features you may like...that didn't have access to. Sometimes, they can fix bugs (like resetting, etc).
There is the rare occasion they can make the device even worse. Sometimes, they add issues. Sometimes, it can even crash your phone. The most common issue is the loss of things like applications and contacts. They will credit the applications that you lose, if any. They will take full responsibility to any damages (or other issues that may make the phone annoying). They will replace it if necessary and credit any lost applications.
You don't have much to lose, and your phone can never improve without these needed updates.
I recommend it.