We've been using Comcast Business / Enterprise Fiber services for the past 8 months. We use the fiber connection for our PRI, main internet connection, and a private line to our facility.
Comcast's business team was by far the easiest to work with and they took the time to sit down with us and help form a solution that best met our needs with the best price. They also took the time to describe exactly how the build would be handled, who would pay for the build (them), and how they recommended handling the switchover with minimal downtime.
Their pricing was very good and comparable to their competition. We found that their SLA was better than the competition in our area as well.
I've found that the latency between our main site across the EPL to our remote facility dropped from ~16ms average with prior service down to 1ms average! In addition our connection going external is consistent with speed and latency always around ~17ms to external major sites. Performance is excellent. Up time has been excellent, we did see one quick ~2 second outage during a scheduled maintenance window that they notified us of well in advance (maintenance was at 2AM).
Originally we where worried about not having a dedicated rep like we had at our prior ISP, but I've found that it has not been necessary at all. From the original build to the few calls I've placed to them (regarding gathering basic info about the circuits) have all been handled timely and with good knowledge by the support center tech that answers (one was escalated quickly), note this is their business / enterprise support center. They do not dump the fiber enterprise customers in with the coax support and it shows.
We have had a single issue with the PRI component of the circuit a few months back. It had to do with their trunk to Verizon. I opened a ticket and very quickly they determined that they where at fault. Through the entire issues they maintained frequent communication with our IT staff to keep us aware of the progress to fix the issue.
Moving to Comcast Fiber lowered our costs (drastically), increased our uptime, increased our speeds.
I highly recommend their Fiber services.