As the famous quote says: 'Exadata is still Oracle!'
In other words, your application will most likely work the same as before - but 10 times faster :)
Seriously, you gave us too few details to say anything specific.
One point: ETL has usually flat files involved. You would put them into DBFS on Exadata.
If you haven't heard about it yet: It looks like an ordinary filesystem for your ETL process but it is spread across (almost) all drives of the storage servers.
"Don't believe it, test it!"
There is little detail in your question.
We have some ETL target database moved to an Exadata dbm and see the ETL runs on average 5 times faster.
(The actual ETL application is not installed on Exadata.)
Unless I'm mistaken, there is a 'Exadata simulator' in 11gR2 for non-Exadata databases. Not sure how useful it is as I've never run it myself.
Certain types of database will run like lightning on Exadata. Others might not even benefit from being clustered.
Try moving it to RAC first before moving to Exadata. It's a lot of money to spend if you can't determine whether or not you'll see the improvements to be worth it (but then again, so is RAC - you need to really understand your application to have a reasonable idea on whether you can cluster a database).