These changes are good for everyone.
If you haven't been using EasyConnect, Presence will continue to work the same way as it did before. Plus, if your router misbehaves and starts blocking your connection, Presence will automatically cut over to EasyConnect so you still have access. The menu bar icon will turn blue, and when you get back to your Mac and you can investigate by opening the Connection pane.
If you've turned EasyConnect on, the main thing you'll notice is that it's now free unless you use a lot of data. If you've prepaid for a number of months of EasyConnect, this will be refunded. If you've paid for the current month, you'll get a data credit.
If you already know you need EasyConnect, you might prefer a black menu bar icon rather than a blue one. You can change this in the Connection pane.
Your Mac needs to be able to receive incoming requests on port 8889. If you are configuring your network manually, be sure to turn off the "Set up my network" option in the Connection pane, as this can interfere with manual port mappings. If you want to use different ports, you can set this in the More Options section.
With DirectConnect, Presence configures your network to allow connections from the internet to reach your Mac. This is done using NAT-PMP (Apple devices) or UPnP (other devices). Other services on your Mac are not exposed, so this is secure.
A number of things can prevent DirectConnect working: your Mac is behind multiple routers (eg. a DSL modem and a separate router or Airport), your router doesn't allow itself to be configured (common on non-home networks, but on some home ones too), or your router is buggy (all too common unfortunately). The Connection pane will tell you what's wrong.
With EasyConnect, your Mac connects to our server, so it is only necessary to make an outward connection. This works in many more situations - if you have an internet connection, EasyConnect should work. This is similar to the way Skype allows computers to connect to each other.
Because all traffic goes via our server, EasyConnect is slower than DirectConnect. That's also why we have to limit your data and charge you for extras.