I would say do your research and then see if Postfinance is the best fit.
In the past it used to be quite good and stable but I get the feeling they are cutting corners on quality and on the programming efforts they are combining between outsourcing and internal employees.
When the system works it is perfect, flexible, nice, easy and practical but when NOT..well..can't say they care too much...probably there is no problem with job safety given it's not a fully private bank. Helpdesk is very polite but what can they do when the software is not completely polished (to be polite).
The partnership with Tata Consulting might be producing some visible effects aside from saving costs but who am I to know about that.
Second...they had a few outages where the whole weekend the e-banking was down (mostly planned maintenance but still..in the current time and day and in the developed world..is it possible for a bank to have its online service fully down during a weekend? no backup site? nothing able to run in parallel while they are working and testing on the other site to see if all goes well? maybe no comprehensive strategy around this or end to end vision as to how it should happen?)
They even had a real outage for all the ATMs on a Sunday 1-2 years ago and it lasted from 16:00 to 22:00. It never made it in the press (probably no reporter was using their service or all were away on vacation) but people were complaining on allestoerungen.ch of how they could not pay at a gas station, how no cards worked (except for credit cards that are not really from Postfinance) and even I experienced the same problem and had to go back home and pick my other card which was with another bank and thus worked. The problem passed as if nothing happened, never heard about anyone getting kicked out over it or even about it coming to pass (outside the few sites that others found to complain); it might have been just a collective bad dream and as in fairy tales when we all woke up ... it was gone.
Then their app....check out when you're not part of the majority iPhone customers what happens..since 6 weeks now...
It works perfectly on iPhone but on Android for a lot of people it just crashes on startup..needless to say no fix since then. Maybe Postfinance is an Apple reseller?
They are still working on the issue. Looks like no one does serious Q&A, the older version that worked on all Android versions was pulled out (so the only choice is the crashing and unstable version); everyone gets a constant excuse that they are working on it, they even released an update but of course it fixes nothing. This makes one wonder if any corrective measures are being taken..like replacing the people responsible for this failure, getting some help from the outside, tracing the errors in the code, reproducing the problem, testing patches. It should be fairly easy for a seasoned programmer (but those are not cheap) to get to the bottom of this.
On the Playstore they have a BOT programmed that answers JUST to 1 star reviews from time to time by just repeating some parts of the sentence (in case it can identify the issue as matching a keyword in its learning DB) and adding to call Support (randomly switching between English and German regardless of the initial language of the review). This makes up for funny experiments by playing with playstore usernames and by concatenating jokes or funny statements to the typical keywords it identifies and reuses in the reply.
If you don't believe me about the Android app...just open the Playstore and read the reviews..makes for a good bedtime story :)
Given this status and 6 weeks..no fix..would you trust such an App with your data and functioning on your phone?
This is something that only each one of us can answer and decide on a case by case basis.
There is also a review I found on the web (though it does not see anything critical..so I would say it's OKish):
https://www.immuniweb.com/mobile/?id=BPk1O7s6
If one really wants to see what's happening, then probably it would require attempting a man in the middle approach + trusted certificates + dumping the traffic that the app is passing through to see what it does + running it in a sandbox and tracing the system calls. Would make for an interesting self study and security evaluation of what you are installing even if just for curiosity's sake.
Would I trust my data to be safe on Android with something that crashes since 6 weeks especially since it's a banking app?
I don't know...this each user has to answer for himself.
At least on iPhone works, it's eye candy, practical, easy to use, nice...