This is a detailed review of my DIGITS Beta experience while using it for past 2 months approximately. This is completely my viewpoint and people may have a different experience in their particular scenario. This review is meant for reference purpose and not to be taken in its absolute format due to variation in usage scenario.
Device used: Samsung Galaxy S6 (SM-G920T), Updated to latest system software
Software used: In-built Multi-line settings and native dialer and message application
Scenario Evaluated: Single device multiple numbers
Experience Rating: 4.8 out of 5
One word to say: Awesome
Pros: Calls, SMS worked flawlessly in both the numbers. I had my primary number and TMobile assigned me one virtual number as a DIGITS Beta number. Activation was glitchy. As soon as I got the registration email, I lost my T-Mobile login. Since I am the primary account holder, it was a big mess losing the account login. The system automatically assigned one of my plan member as the primary account holder. I worked closely with T-Mobile Twitter support. Support agent BrookeG worked hard with backend support team to resolve the login and the primary account holder issue. Things are fine now. I activated my DIGIT line from https://mydigits.t-mobile.com/consumer. So far, as promised by TMobile, I did not see any bill hike for using Beta. Messages are delivered properly to both TMobile and Non TMobile users when sent from Beta Virtual number. Call quality was carrier grade to both TMobile and non TMobile user. As a whole, I could not differentiate whether I was using primary line or the virtual line
Cons: Galaxy S6 sometime became hot. Possibly a software issue when multi-line setting is activated. Also, message delivered status became unavailable after I activated Digits.
Overall, I am going to stay with this possibly even after Beta is over if the pricing is nominal.