Devlelopers building on top of Nxt should pay attention to these threads, there are some important changes in Nxt to be aware of:

https://nxtforum.org/core-development-discussion/adapting-client-side-code-to-the-fee-changes-planned-for-1-7/
https://nxtforum.org/core-development-discussion/new-fees-and-size-limits-in-1-7/

Ordinary users, you won't notice the changes so don't worry