Quick, general answer.
Mobile b/band is crap, speeds never anywhere what's advertised and coverage is too patchy.
It's cheaper and better to use wi-fi (built in or a stick) and find a free spot - loadsa hotels, coffee places and pubs do it.
Our local does.
When you get a connection, it's better and faster cos you are connecting to someone else's wired broadband.
Mobile companies are very naughty withe their contracts and will cancel your SIM if you don't use it enough and you lose any credit on it - cannot be re-activated.