Am in a bus at the moment. Just before 2 minutes I was standing at the bus stop, in the rain (all thanks to the recently changed bus time without replacing the old time tables.). Before standing for long, I just decided to put on the rain cover I had bought for such occasions. Thought it's best time to give it a go, before trusting it on day long treks/hikes. Picture here shows the level of accumulation of water on it. Regarding waterproof-ness, I will add an update to this post soon (once I reach home).
Update: When I got into the next bus(which had to hold up for me:P Really I love National Express and prefer to travel with them, when ever there is an opportunity, cause they really *listen* to customers. They do!), I took the rain cover off and bag was pretty much dry, compared to the rain cover itself, which was dripping wet. Which means it really dealt with quite a lot of rain. This gives me a but of confidence to put this Takona rain cover to test one more time, may be when am hiking on Snowdonia Mountains:D..