Very pretty. I can see you like landscaping the terrarium.

In my opinion, that setup would be great for a small gecko or lizard, if you took away the UTH and added some branches. Your ball python will probably outgrow it in maybe six months or so. Also, since they tend to stay on the ground (though there are some exceptions of climbing ball pythons), the vertical space will not really be used much. I might stick a branch in there just to see if he'd use it.

Assuming the lamp is mainly for the plants and not for heat, be careful about its wattage. You didn't mention the type of bulb you're using; go with a compact fluorescent that won't emit a lot of heat. Incandescent lights tend to dry out tanks in no time and will overheat your ball if left unregulated.

There's a cheap, digital, two-side thermometer and hygrometer you can get at Wal-Mart for $11 made by Acu-Rite. Works pretty well and a lot of people on here use it.

Finally, you want to be very careful about using soil in there. Soil that isn't made for reptile substrate can have bugs, bacteria, and fertilizers in them that would cause problems if ingested accidentally by the ball python. Their bodies are not equipped to deal with foreign bacteria.