Others in this thread have covered most of the points already, but it is mainly software support for certain key things I want to do using my phone, such as online banking.

I realise most of this is just anxiety about taking the plunge and seeing what it's like, so if I have money to burn I might just buy a second phone just to see if it's a viable option for me.

But yeah, I wish mobile Linux was popular enough for there to be support from key service providers. Though it might be a long shot since "desktop" Linux is still growing and we haven't yet seen the support shift.