I won a Brewkeg 25 in a competition, have put through maybe 8 batches so far. I also have a fermentasaurus which I still use.
TLDR: love it. If I could afford to replace the fermentasaurus with another one, I would.
It's well made, solid, and the company seem responsive about spare parts.
The lid is transparent, so you can shine a torch in to see how your krauesen is looking. Plus the collection bottle at the bottom let's you see rising bubbles. This puts it well ahead of other opaque stainless fermentors. Pressure fermenting is great, for many styles. Great for closed transfers etc.
I've been letting the wort settle a couple of hours before pitching, then remove the bottle of trub and discarding. Just makes for less bottle swaps later and cleaner harvested yeast. I'm usually swapping the bottle as it approaches FG then again after clarification.
Downsides, not many. It's pricey, but most stainless conicals are. The lid doesn't always seal perfectly, but if you take your time and use keg lube it's good. Can't think of anything else bad about it. Even the size is pretty good, fits in a pretty small fridge. The videos are all about going extract to glass in 7 days by fermenting warm under pressure. I don't much care for warm ferments, and aren't in that much hurry. I've been doing 2 weeks grain to glass very easily.