Shimano E-tube Di2 Wireless Unit

Presumably you mean the EWWU-111? Depends what you want it for and if you really need it. I have it in order to change the screens on my head unit using the hidden buttons on the shifter hoods. If you intend messing about with your set up using your phone or an iPad, i'd say its easier and less complicated doing it directly from a PC.

The main advantages for me have been summed up by the previous two respondents - showing Di2 battery charge level is the greatest benefit for me, then being able to use the hidden hood buttons to ‘swipe’ through pages on my Garmin, followed by the surprisingly useful display of rear gear selection on the Garmin.

Using the hidden buttons really is so much better than having to remove a hand from the bars and then trying to swipe the screen - especially on roughish ground, or descending etc when you want to keep complete control by having two hands on the bars and also when really, really flagging on a particularly long or gruelling ride - you don’t realise just how much effort it can actually be when knackered to remove a hand and swipe a screen! I kid you not...!

As for E-TUBE software on my iPad via the Bluetooth connection - hmmn, not worth the hassle trying to get it to work when I simply plug the cable into my pc and can have software updates and configurations sorted by the time I’ve managed to get the iPad to even see the system!

PP