I don't think it so much gets a bad rap as it's just a bit more overlooked. I think that's easy to answer (for me) - I've repeatedly stated that it's actually my go to/return to Ubud resort. It's very, very welcoming, and it feels just right. There are reasons why I wouldn't send (especially first time) Ubud/Bali guests there. I've often said that it's arguably the least 'dramatic' Aman I've seen, yet possibly the most homely.
I think the biggest factor for me is that the resort feels a little too small - obviously it's not particularly comparable to Kila, but there are just so many places to lounge around at (or even walk around at) Kila, whereas the walk from your room to the only really lounging space at Dari takes about a minute, if that.