my only critique, and its quite anal and small, is that to the left you can just start to see a few large stars (or small galaxies). would be good to widen the picture a few more millimetres just so all significant objects in the picture are present. but as i said thats just being very anal, i cant see anything else wrong.
will be interesting to see what the hydrogen filter will do.
actually apparently i didnt hit the minimum word count above so i must try to find something else to critique :s
maybe try and sharpen up the smaller galaxy to the right or adjust the colours a little so we can see some detail in it.