> So my question is: is HTTPS over open wi-fi trustworthy?
As trustworthy as it is otherwise, so generally yes.
Since Android supported arbitrary VPNs (as of ICS) I use OpenVPN to home on my tablet (as I always did with my netbook) - that way I should be no more unsafe, even for unencrypted protocols, than if I were sat at my desk. It does add latency of course, which in less than ideal conditions (an iffy 3G/GPRS connection) affects throughput too (on top of the small amount of packed wrapping overhead in the VPN protocol itself), but I've not found that to be noticeable for my use pattern.
As trustworthy as it is otherwise, so generally yes.
Since Android supported arbitrary VPNs (as of ICS) I use OpenVPN to home on my tablet (as I always did with my netbook) - that way I should be no more unsafe, even for unencrypted protocols, than if I were sat at my desk. It does add latency of course, which in less than ideal conditions (an iffy 3G/GPRS connection) affects throughput too (on top of the small amount of packed wrapping overhead in the VPN protocol itself), but I've not found that to be noticeable for my use pattern.