I agree about learning from others, but disagree about offering criticism. I do it very rarely, because I don't consider myself anyone's teacher. Well, apart from the hundreds of people I teach English to...

One should only criticise people's work if they ask for one's honest opinion. From my point of view, my pictures are exactly as I like them, I don't post unless I think they're good enough and if other people find something wrong with them, it's usually a matter of taste - and we're all different. I don't need criticism, or to hear I could have done better... sometimes it's better, sometimes worse, depends on many factors, like use of real weather or setting things up artificially for best effect, the model used, the time taken etc. I'm not aiming to be the best on the V which would be impossible, or even the best I can be... I just post for fun, and to be honest, to hear some nice comments... in life, it isn't often that people praise you, at least not when you are an adult. I miss that about school... Well done! A+ and so on...

It irritates me when almost nobody can be bothered to write at least :) or Nice!
As for those people who post something that looks terrible and write 'Enjoy' underneath or something, it is probably best not to ruin their illusions. After a bit of time in the forums they can see what the standard is, and will probably ask for some tips if they care. The reason usually is that their computer is really old, or that they mainly fly seriously and are just sharing a screenshot to be social...
So, best not to criticise others....unless they ask.
My two cents... Krigl