the device turns on based on gate voltage. some times a small series resistor is added in series with the gate for other reasons. the gate acts as a fairly large capacitor, and sometimes the gate is driven by an inductive source, in which case there can be enough ringing to cause the gate to turn off accidently. a small series resistor is added to damp this out.
otherwise, there is nearly no need for a series resistor.
further, you no longer need feedback to keep the device from saturating. the FET will still turn off very fast. often, the threshold may be 5V, but the gate will be driven to 10V and back to 0V. this mainly causes a delay -- the gate drops to around 5V, then the device turns off, then the gate drops to 0V.
so, basically, just apply a high voltage (above the threshold) from a low impedance source and your done.
The FET will stay on until driven low -- the gate capacitance is high enough and near no current flows through the gate. so in some cases, you'll need a pulldown.
Also, transconductane is lower, but this usually isn't an issue. but the required Vgs to "saturate" the device may be a bit higher then the threshold. but this does make the "emitter follower" equivilent fairly poor, as the gate may need to go 5-10V above the source. but methods exist to allow this to work for rapidly switched circuits.
lastlt, "saturate" is backwards in FETs -- the physists decided that "saturate" would be the point at which current is "saturated", which makes the "saturated mode" of the FET similar to the "linear mode" of a BJT... likewise "linear mode" for FETs is very similar to the "saturated" BJT. its somewhat annoying if you aren't aware of the terminology differences.