I've been using Allo when it came out, it's a good app, it's clean, has plethora of features and most importantly is fast (thx google superservers), I really have no idea why they re-doing it again, it's a perfectly good app, invest more money in marketing or whatever, it's a good competitive product. Biggest issue with all chat apps is that your circle of people might not use it, but since they include allo and duo with the phone preinstalled its slowly becoming non-issue. I personally use Allo and Duo and I like both of them a lot.
I wish that Allo and Duo had apps for windows and tablets tho, otherwise no issue whatsoever