Re: Is it proper?
I think teaching aikido can be difficult, because any technique almost always is wrong. i.e. we learn how to do it badly and improve. This is unlike some things e.g. learning multiplication, where it is either wrong or right.
The trick is to tell the student what they need to hear at the time so they can grow the most. If the teacher is new, have patience - when I started teaching I found it hard to comprehend how people couldn't do a ukemi. I just demonstrated and expected people to be able to copy!
As long as it is not an ego thing for him/her, take these negative comments as a bit of a compliment; it means you are ready to hear things that can improve your technique. Of course, if it doesn't help and it just makes things complicated, the extra advice is useless.
IMO aikido is very simple - it just takes a long time to realise this, then even longer to be able to achieve this simplicity. I also believe it can't be taught by word of mouth or explained with words and has to be experienced over time. The words are the equivalent of 'pointing at the moon', and shaking the finger harder will not increase the students capacity to understand.