Since I'm no balance know-it-all, I'm going to critique based off aesthetics
It looks much better than my very first attempt at mapping, so that's a start, but it isn't of the same standard as the rest of the maps in game.
For demonstration purposes, I'm going to butcher my 1v1 map.
Non-playable areas: Whilst what I create isn't Max Power levels of detail, it does mean it can look acceptable at a glance during online play.

This, considering it's a glacial map and thus there isn't much you can do in the way of splats and splines, is probably acceptable detail. Four or five different tiles overlapping at certain strengths so the stone and ice can be seen beneath the snow, as well as making the stone appear it has an icy coating with a layer of blue glacier tile. Broken up by strong snow banks and the added lighter tile on the cliff face to the left, with blended cliff faces to ensure the terrain does not appear samey.
Playable area: The easiest way of adding detail to the playable area without overcrowding with objects, which by the way I like your placement of, not too many but some well placed and varied items to make that convincing, is to use splines.

In this example you can see how splines are used to divide the terrain, how they can add to the variety of the terrain on show, as well as hiding the edges. Never be afraid to stick to a pattern, be creative, stick splats on top of each other, put two splines next to each other, have wire splines going into splats etc.
This is how it would look without splats and splines:

You can see the edges don't blend very well, leaving blocky lines and awkward transitions, leaving a very unconvincing atmosphere. The snow tiles are more realistic as you don't always need to use splats for these natural looking tiles, but sometimes a snowy/dirty/slimy spline adds subtle differentiation. Open the Relic maps with an SGA reader, their maps are full of very subtle splines that help keep the map looking different. No splines, splats and varied textures makes for a soulless map, it may play like the ebst map in the game, but ultimately your casual gamer is not going to like playing it.
So how can this help you?Make sure you have lots of tilesets to choose from, take this for example (laid out in a matter of minutes, so not realistic as such, but using varying levels of transparency):
http://i.imgur.com/x0qgATc.jpgWhen looking to combine urbanised tiles with natural tiles, as you did in yours, best not to go right into each tile without partly obsuring the edge with splats or splines, adds little details that help to make the transition smooth.
http://i.imgur.com/k3ohRms.jpgI appreciate I'm not the best with desert terrain, I've never used it before, but you get the idea. Combine splats and splines to obscure edges, create natural looking transitions (ignore the top part of that image

) as well as to provide variation to areas that would otherwise be default tile.
I hope this helped!