I have a Brewzilla 3.1.1 and it's worked well for me. It took me a while to get my efficiency levels up but, as was mentioned, there's a ton of YouTube videos out there for advice and also on this forum as well.
However, I want to up my volume a tad and so I was looking really forward to the Grainfather G40 release but the price is really off putting.
The new features on the Gen 4 (or should I say the features copied from other manufacturers) are going to be:
Wifi control and internet connectivity (nice to have but not really necessary)
Top mounted controller which can be tilted and disconnected from the unit (crawling on the floor with the Gen 3.1.1. is exercise for me)
The base will drain out completely (I just tilt the current version ;-))
CIP (Cleaning in Place) functionality (that's what the shower in my bath is for)
Spray jet/nozzle (I use a €3 wort siphon made of plastic)
Sight glass to see and measure volume (there is a kit on Aliexpress to add this to the Gen 3.1.1 if you're handy with plumbing)
Anyway, according to what I've read, they have a shipment of Gen 4's due to arrive in Australia from China at the end of December and another at the end of January. Both are expected to sell out immediately, so as
@chillipickle said, we probably won't see them in the UK until the middle of next year and even later for me in Ireland.
However, that's a good thing because Kegland is notorious for having big issues on the first release of a new product (the Gen 3 was a nightmare and their RAPT fridge is not getting good reviews).
And by the way, I'm not a Kegland fanboy - it's just that our options in Ireland are limited and Brexit has meant that many UK suppliers won't ship to us (not surprising given all the red tape and delivery problems).
But it might be worth waiting a while before buying the current version (which is probably what I'll do for the 65L) as I would expect we will see heavy Gen 3.1.1 discounts once the "Brew-Tubers" get their free Gen 4 kit and tell us how great it is...