They don't leave in honorifics like -san, -kun etc. and pretty much everybody calls eachother by their first names. For example, in one manga (that I bought from them before I knew about their translation policy) there are office workers calling eachother by their first names at work, which would be really weird in Japan's strict hierarchical society.
It also leads to readers having no idea about subtle relationship changes. Like if person A has been calling person B by their last name for three chapters, and in chapter four their relationship develops to the point where person A decides to switch to the much more intimate first name.
I also dislike the fact they change the currency from yen to dollars. Not everybody is from the US, and if there's going to be a foreign currency anyway, I'd rather it be the one used in that country.

I just can't support Renta since they don't preserve Japanese culture in their translations. Other publishers are great, Renta sucks.