I like the strings of lights. And I would add a dark cloth-like panel into the small crack between the wall and the wood/plastic ceiling (for sun protection purposes. There would be a switch right inside the back door that would make the panel move out.
Yes, it's artsy. Yes, it's bohemian. I get that this might not be YOUR style. That's fine. At the very least, though, recognize the fact that they have artfully made a cool (temperature) place to relax and it will subsequently lower their cooling bills!