I got my invite on 12/24/14 and I have managed to ride 4 times on Zwift Island. Here are some initial thoughts and feedback on your beta product, some of which have been observed by others:
AI Riders - it would be nice to see what power level these AI riders are running at by putting their current power on/above their 3-d outline. In addition, there should be a few different styles of AI riders (sprinter, mountain, constant, random) that exhibit different power performance profiles as they zip around the island. It would also be nice to select an AI rider to run at a set power level so they can act as a pacer for those who want to track/improve their individual performance.
Drafting - I can’t really sense when I am in someone’s draft but that is probably because I am using a Kinetic Trainer (dumb trainer); it would be nice to have a draft indicator that shows what the incremental power saving(s) are dependent upon how many meters I am behind the rider in front of me- this would work even with a dumb trainer.
Average Power - be nice to have the overall average power shown during my curent rider Current power (instant, 3s, 10s) would also be nice as well as average power for the last lap around the island. I realize that the application already displays instant power and that is indeed very useful.
Group Rides and Races - post times (via email) of when a group race/ride is going to start so we can all drop in for the start of the race. I currently drop into Zwift Island and pedal like a mad-man to catch up or wait until someone catches up to me - I realize I can use the follow a rider option but that messes with my precious Strava data.
Power Sensor (Hints and Tips) - I have discovered that using a USB extension (1 or 2 meter) for my ANT+ sensor is essential to no ANT+ data dropouts. My power meter is a Stages power meter which is located on the left inside crank of my crankarm. By placing my ANT+ sensor underneath my bike I have had ZERO data dropouts from my Stages Power Meter/Cadence Sensor , my speed sensor and my HR monitor.
Computer Platform - I guess I have been fortunate in this area as well . I have had no system crashes and my Windows 7 (i7 processor running at 4 GHz) has been running just fine.
In summary, you have a fantastic product and I believe it will gain broad acceptance within the cycling community. I had been a Trainerroad and a TourdeGiro (TdG) user before using this product and this virtual riding environment blows my mind.