The brand’s YouGov Buzz rating, which measures the positive and negative things said about the brand, has fallen dramatically since the service was disrupted around the world.
It stands at -39.4 today (14 October), down 51.1 points from 10.3 on 10 October, the day its messenger services crashed.
The brand’s quality, reputation, impression and recommendation scores have also fallen significantly since then.
Parent company Research in Motion (RIM) also suffered a drop but not as steep as the handset brand. Its Buzz rating stands at -9.5 down from -0.1 on 10 October.
The company has today (14 October) restored all its services but up to 70 million users around the world are thought to have been affected by the outage which started on Monday (10 October).
Blackberry suffered a similar drop earlier in the summer when its reputation was tarnished by the association with the rioting in London.
Its buzz dropped to -7.9 from 9.9 between the 8 and 11 August as reports emerged that its BlackBerry Messenger service (BBM) was used in the organisation of rioting.