You can still make an interesting level using a desert theme. There's nothing stopping you there.
The cacti looks bad and doesn't do the level any justice. As others have said, the perspective is wrong and also the colouring and shading isn't great either. I do, however, think having cacti in there will help providing they look ok.
You're going to need to spice up the terrain a little bit. You can add other plant life other than cacti. If you look at the following image, this gives you an idea of what I mean:
Another thing to consider is that a desert isn't a straight flat surface, like it appears in your level. Simulating a desert's dunes in Graal will be difficult but there are things you can try that are inspired by it. This will require using a different set of tiles for the ground than the one you're currently using. Although it's not a stellar example of level design, see what's done here. Must ask you to disregard everything that isn't brown/yellowish.
http://forums.graalonline.com/forums...3&d=1045758647
You could also use cliffs. I can't describe exactly what I mean but if you see the following image, it should give you an idea:
My last piece of advice might be a little bit ahead of where you want to go with this. Currently, the graal's desert tiles are pretty plain and could be improved. I would recommend looking at changing these - they can be improved in subtle ways. The current desert tiles are quite flat, where as sand has ripples. I remembering seeing something on Bomy Moon but I can't seem to find an example now...
Hopefully I've been of help. I don't think you should just stick to scripting. If it interests you, continue! A lot of people have started out with uglier work than this - not just on Graal but everywhere. Good skills rarely come naturally, it's the desire to have them that counts most. You can learn, it just takes a little bit of time, lots of practice and, most importantly, good amounts of feedback. I remember when I used to show my levels to Snakeandy and WanDaMan. They were rubbish but thanks to their feedback they got better. They're still not great but without the practice + feedback I would have never have progressed.