C4 is under the IC, which may (or may not) do problems, regardless which side of PCB you place it actually. The reset is better to connect via resistor to defined level than to leave floating. Usually there is also capacitor there to delay start until power is stabilized. I would put big capacitor near the stabiliser (also I think, it is recomended by manufacturer of the stabiliser for a reason), but maybe if you have good batery and short wires, it could work too. Also small capacitors between GND and VCC as near the IC as possible are common to reduce noise. And reset button is usefull add-on, but not necessary. Anyway I think, it could work as it is (with the reset defined).
If you have some particular application in mind, then you may use also different layout and/or get more connectors for some pins (some of my "arduinos" does not look like Arduino at all, having all periferials on the same PCB instead on some shields.
also http://download.gilhad.cz/arduinobb_12.jpg this is fully working arduino, which I used many times - so you do not miss anything critical (those LEDS are not necessary)