I have a Wattbike for almost a year now and used it all year round, I’ve improved my cycling, running and overall health dramatically as a result. I don’t use Zwift so can’t help on that, but understand updates have improved gear response, I use FulGaz.
It save masses of time as sometimes I don’t have time too get to a trail centre but an hour or so on the Wattbike can give a very good workout.
It’s the best thing I have bought for cycling and health and fitness and has had the biggest impact, as I can ride when normally I wouldn’t have time too, before work, other weekend commitments etc.
The only bad thing is I shouldn’t have procrastinated and bought one sooner than I did, oh and the standard saddle wasn’t comfortable for me at least.