I certainly could add a couple more Oases to the east of the little dunes, however the large Oasis was a decision to give the continent an "eye" in reference to that specific continent's name. It aldo has implications later on in the game, so breaking it up wasn't something I'd be particularly fond of from the standpoint of my plan.
I know it's hard with the tile set, but try to break up the straight lines a little more, particularly on the natural formations - mountains, rivers, forests, coastlines, etc. Straight lines don't occur like that in nature - for a good example on your map, look at the main continent's southeast, where the grass meets what looks like wasteland; I like the way that is for this particular tileset. Try to do things a little more that style along the coasts and forests, in particular - I'm not sure what you can accomplish with the river, as they're extremely limited given the tiles.
Well, the main continent is finished for the most part, but tweaking is always a good idea, right? I'll definitely take your advice, it seems like common sense, and I missed out on that.
As for the river, i can always give it more of a curve in the "rapids" portion where it's narrower, as well as the bottleneck just north of the "delta". For the mountains, that portion on the East side with snow, is definitely too straight, it plays a nominal role and I haven't got around to making most of the towns yet, so I completely overlooked that. In any case, I'll do what I can.
The only area I don't want to change too much overall is the northern offshoot on the initial continent. After all, the map was made just by drawing randomly with a tile and working and from there XD