oh no! not another slow cooker thread! But tips wanted please on what features look for..

[Orinoco]

How many heat settings?
How big?
Is there anything else I should know?

Thanks

..and should I just buy the biggest I can afford, or is there a hidden pitfall?....

I have the Rival one, its quite big and has a high and low setting, it also has a timer for upto 20hrs i think and then automatically switches to warm when finished and stays warm for 4 hrs, was about forty quid or forty five from John Lewis.