yes, SMM10 is/will be a free upgrade for SMM9 customers.
SMM10 is more polished and does not have any drawbacks.
Important new features are
- navigating directly to a contact by clicking on them (imported addressbook to Sygic)
- speedcams over internet
- traffic over internet
- weather over internet
- swipe to scroll instead of having to click a button
- map data will be upgraded for free as well, but it is also possible to use the old maps

I've also released a video about SMM10, check my signature to head over to my youtube channel.