If you gnat's a$$ it and measure it out, the TGM Hetzer is slightly larger than 1/30. Just like the recent TGM Panzer IV and Panzer III are slightly larger than 1/30. They're all more like 1/29-ish.
I personally think 1/29-ish is actually the sweet spot of these models, as the difference is only a few millimeters, and 1/29 scaled stuff seems to look good with the widest variety of figures.
The TGM Hetzer looks great with First Legion/W. Britains/War Park figures like Mark mentioned, but it also looks decently accurate with the slightly larger TGM figures. I think the commander figure for the camo Hetzer above looks pretty spot on size wise.
The Jagdpazer 38(t) "Hetzer" was a really small tank destroyer. Here's some video of a Swiss G-13 reproduced as a Hetzer (same exact external dimensions) with re-enactors riding on it and a tank commander standing in the hatch. Gives a good example of just how tiny the thing really was.