First question I would have is on the new Bluetooth's ability to work with older versions. It's not helpful to adopt the new version for designing an IoT device if the bulk of the smartphone installed base cannot work with them. If there is no backward compatibility, this new version will need to wait for adoption and extensive deployment in new smartphones before it can be useful to IoT device developers.
Rich: My understanding is that, by its very nature of being "low energy" it cannot be backward compatible with 'classic' BT. However, I believe both modes could co-exist in say a dual-mode phone. And they probably should because they have different purposes. What is happening here is that BT LE is going after a market that has been dominated by other low power wireless protocols, such as ANT+.
All new Bluetooth versions are designed to be reverse compatable with previous versions of the specification and v4.1 is no different.
The only caveat is Bluetooth Smart products that impelement the "Low Energy" feture introduced in the v4.0 specification. Bluetooth Smart products (such as the latest generation of fitness monitors and other wearables) are compatible with other products labled Bluetooth Smart or Bluetooth Smart Ready.
It seems many devices are going with wifi - range being the largest issue although being able to work with existing networks, and the internet another. You would need to have repeaters in a house unless the range was boosted, and as mentioned before backward compatibility with existing networks? I can see in cars and such, but how in a house, and between "things" will it work?
Backward compatibility and usability for app-cessories such as wearables are both very important aspects of this update that remain sort of in question. Still, the fact that this update allows for maintenance of connections with less frequent manual intervention is a major boon, as that has often been an issue with Bluetooth connectivity. Expanded time intervals should also benefit the user experience.
It's great to see the new improvements in BT in terms of power consumption and RF, I am wondering if BT ever going to implement a more secure and solid connection to become attarctive for other applications such as medical and Industrial?
security features has been improved in BT since rev 2.1, however, still not fully adopted for medical applications (e,.g: Body Sensor) to my knowledge, instead other standards such as 802.15.6 is being sought.
personally, I think with current low power support in BT (1mW) and a more robust security implementation , BT can easily become a choice, mainly becuse it is using a shared spectrum.