Once you start slapping the other stuff on top the topographical details shouldn't matter so much. This is the first time I've used the tutorial but I think one gets a better mountain effect using bryce .... still it looks good enough and we should go on to the river stage next or we'll be fiddling with this until the Centaurs come home. I hope at least you're getting a better feel for what photoshop can do.

p.s. the rivers are going to be tough without a tablet