The Paris Pass

No. For 2 days you will not get your money back. Just buy a Carnet (book of 10 tickets) for bus and Metro rides (13 euro). If you want to fill your time with museums, the 2 day Museum Pass for 42 euro MAY be warranted, but probably not. In 2 days there is only so much you can do. At 117 euro, the Paris Pass is way overpriced.

The Paris Pass is not a pass, it is a marketing gimmick where they put a Paris Visite transport pass (very overpriced even if you buy it yourself on arrival) and a Museum Pass (maybe a good idea) and some other coupons, put it in an envelop and then add a hefty fee on top of that.

You don't need a pass for transport for two days, just buy an RER ticket into town from the airport (9.75) and a carnet of ten ordinary metro/bus tickets for travel around Paris for 13.70. You can share the tickets with travel partners and when you run out buy another carnet although in two days, you probably won't need to do so.

You can pick up a two day museum pass on arrival if you will be visiting a lot of the sites included.

This will be much less expensive than buying a 'Paris Pass'

The above replies are spot on. To clarify further, there's a Paris Pass, a Paris Visite Pass, and a Paris Museum Pass. They are not the same, and yes it is confusing. The Museum Pass can be a good deal if you are seeing a lot of covered things, if you are going to some places (like Versailles or Musee D'Orsay) where skipping the ticket buyers line saves a lot of time, or if you want to go more than once to the same place (say, taking two shorter visits to the Louvre instead of one more tiring marathon).

Here's the list of what's covered by the Paris Museum Pass, so you can see if it's worth it to you: http://en.parismuseumpass.com/rub-museums-monuments-by-name-5.htm. A two day pass is currently €42. If you do want one, you can buy it in Paris easily, so don't pay extra to buy it before your trip.