To be precise, which exactly should be improved?
"Graphix sux" is what you will hear a lot from people, just in more colorful words and longer sentences.
Now, I'm not saying you need graphics worthy of an official game, I'm saying your graphics right now are in the term of "rough". You can improve the graphics a bit, but focus more on smoothing it out. Just take a look at your screen shot, and you will realize exactly what I mean. Those pictures would look a million times better smooth, and it would give the players a "fake" feel of good graphics (most won't even realize the graphics are that bad).
- are you talking about the style (big pixels) or about the execution (how these pixels are arranged together)?
- you mean the 3D view (left side) or interface (layout, portraits, menu on the right, movement buttons), or maybe all of them?
- what you mean by smooth?
Maybe indeed I should do that...
All of this is, of course, things you should be considering in your beta version. Right now your in alpha, so I can't really force this stuff down your throat and tell you to do it now. But it must happen some time in the foreseeable future. You said you were working alone? Why, I'm sure their are many people who would be willing to do this little game with you. At least try and get some help.