Have you all downloaded... and activated it?
I think that for every million they spent on writing the software, they spent ten million on lawyers!? Did anyone read (one-tenth of) the privacy notice?
¿What good will it do? - for who?
I think that it will be of little or no benefit to us, the users, but will give the government epidemeologists some usefull data.
¿What are the limitations of the app ...and the system?
The app does not know if you were inside or outside when you were close to an infected person.
If you were at a venue where an infected person was - does it know if you were within ten metres of the infected person? If the venue is correctly "social distancing" you should be at very low risk anyway?
Are the tests actually useful to us? - if you get a test within half a week of exposure, there is a strong possibility of a false negative. If tests were reliable and available... they would help.