The ram usage is ok if you disable some of the useless shields.
I hate the interface and it doesn't have auto scanning so I would never put it on a pc I fixed.
I also haven't seen the new detection rate first hand.(and yes I've scanned infected pcs with it. I always ended up just using sysclean on them in the end.)
After switching from CA (formely Etrust) to Avast, I must admit I am quite used to it now and have found it to be good on my system.
I think that people's systems can determine how good an app works for them. So sometimes a really good app gets a bad write up simply because it doesn't gel with the users apps and specs.