i would say get a mifi, unless you already have a spare smart phone laying around doing nothing.. as for pros/cons, you might get terrible speeds if you start connecting a lot of devices to the hotspot, but same will go for a mifi device.. also, if you are using more than your monthly allocation of data, youll end up having to buy more which will be more expensive than buying equivalent ADSL data..
other than that you will be golden..