I've been trying this new feature and I think it is mostly good - the only problem I have so far is that I have one site with a custom fill in set up for it (I live in the Netherlands and some fields have a Dutch name and won't autofill)
Now when I open a new site and store the credentials this pops up (top right of my window) and asks me if I would like to update the custom fill in - which of course I don't as it only applies to one specific site and is not a username/password. I don't have a screenshot now I will try and get one and add to this message.
I now have a screenshot - this popped up when I was entering an address as my contact address in the US when on holiday - it wasn't username/password stuff
The new "improve save and fill" keeps generating pop-ups offering to save every email or phone number I enter. VERY annoying!
Then it keeps offering a new password instead of offering to fill in the saved identity for websites.
These will make Last Pass unusable if it is forced on us.