The Aristo Li'l Critter is best described as an industrial switcher. Though there is no prototype for it, it does resemble many of the small units found at steel mills, cement plants, power plants, etc. all across the country. It could also be used in yard areas shunting freight or passenger cars to various tracks.
This diesel shares many parts with the RS-3, including the power brick. As a result, it is a very smooth running locomotive which pulls well on level track. The diesel comes in a variety of road names, including some industrial names. The paint work is excellent, and the lettering is very crisp. I have one for the SP and my wife, Marcia has the Hershey's Chocolate version.
The unit comes with Aristo knuckle couplers. Hook and loop couplers can be installed, but as with the RS-3, this is a difficult task which requires some cutting on the pilots. Kadee makes a coupler conversion kit (#788) which works real well with this diesel.
There is one control switch on the side of the locomotive which turns the motor on or off. The lights always stay on, and there is no smoke unit in this model. There is plenty of room under the hood to install a sound system, but the cost of the sound system would be more than the cost of the diesel.
Weight can be added for more traction, but since this unit is not meant to pull long trains, I would not recommend doing this.
This is a fun diesel to run, and because I is unusual, ,it will solicit many comments from people viewing your layout.