What Effects Will Users See?
From the users' point of view, all the detailed changes between version 1.0b and version 1.1 add up to just two things: reliability and interoperability. The good news is that version 1.1 implementations will interoperate with one another and will work much more reliably than under version 1.0b. In particular, low-power modes (hold, park, and sniff), security procedures, and the master-slave switch will work much more reliably. The bad news is that low-power modes, security procedures, and the master-slave switch are incompatible between version 1.0b and 1.1. Basic connections will work between version 1.0b and 1.1 implementations, so they are capable of connecting and transferring voice and data. Don't expect to use security, low-power modes, or the master-slave switch if you have incompatible versions, however.
This means that some profiles are likely to work as long as security isn't switched on. For instance, the Headset Profile or the Generic Object Exchange group of profiles (object push, file transfer, and synchronization) are compatible. However, the LAN Access Profile relies upon the master-slave switch, so it will not be possible to connect several 1.0b devices to a 1.1 LAN access point.
Overall, the increased reliability and much-improved interoperability of version 1.1 is good news for Bluetooth devices. The specification also is now much clearer, which is good new for anybody starting out to implement Bluetooth.