Less than 1/10th of what LA had. A very small fraction of systems in Philadelphia, Boston, NY, Pittsburgh, Chicago, etc.
It is what one might expect for a small town like Houston was then. It may very well have been impressive given the size Houston was then - I'm not qualified to say yes or no to that.
Post the figures if you got em. A quick google search reveals the following mileage in the first decade of the 1900's, which is when Houston's total mileage peaked at about 170
Denver: 164 miles
Detroit: 202 miles
New Orleans: 169 miles
New York: 357 miles (appears to include all rail-based modes)
That places Houston in comparable range to other cities of the era.