Yep, dont take the base up above 1.2v much or you'll quickly short the supply.
The only problem with a simple circuit is the temp isnt particularly stable, the transistors properties change as it warms up and that in turn changes the heat dissispated, worse case you can have runaway.
A simple circuit is ok on a simple application, if you want something more controlled this is a cool cicrcuit, but a lot more complicated, this circuit monitors and controls the temp:
**broken link removed**
Maybe a power resistor would suit your application better.