I have been using ACT broad-band (10Mbps, 50GB limit) fiber for over 9 months now in Bangalore, Banaswadi area.
SPEED: The speeds are reasonably good .You may not get 10Mbps, but 2-3 Mbps is probably what I see. The speed is not consistent , however, on bad days it can go down to 1Mbps also.
UPTIME: It works most of the time. It had gone down a few times in the past 9 months. They do take 2-3 days to fix it.
CUSTOMER SUPPORT: It is not easy to get the customer support on phone. email would work although it adds more delay. But, in general they are far better than BSNL etc.
INFRASTRUCTURE : This is the worst part. The fiber comes in over trees, tied to branches (just like our old cable TV) crossing others plots etc. On the top of it, they need to install a fiber-to-ethernet box and draw power from your house 24x7. Even the connection for your neighbors would be tapped from your box ! If you are lucky to have some one nearby who has already installed the box, you can also tap from it.
Overall the service is OK, do not expect 10Mbps speed and all, it may give 1-2 Mbps in practice.