Given the bike is your primary mode of transportation, I'd focus first on function, and the parts you have are fine, but make sure cables and pads and tires are good to go.

Given the bike is your primary mode of transportation, I'd focus second on where your body meets the bike: pedals, saddle, bars. Make them what you want.

Given the value of the bike as it is, I'd just go with the elbow grease for a beauty makeover.

1-Functionality is first; tuned, lubed, adjusted.
2-Fit and Comfort; where you touch the bike.
3-Appearance; a little makeup goes a long way.....and I'm not gonna go further with that one.

Figure $100-$150 max to make it right for you. Over that, start thinking about a different bike.