Yes its a good buy assuming you will use public transportation more than 5 times in one day.

A Mobilis for zones 1-2 (which is what you need) will cost 5.60 euros. If you buy tickets in a carnet of ten then each ticket costs 1.11 euros. So five trips using indivudal tickets will cost 5.55 euros and six will cost 6.66. So the Mobilis is a good buy if you use it more than five times.

You can buy two at the same time. When you use it you put the date on it and it is good for that day.

Its pronounced for or less like it looks with three syllables Mo-bi-lis.