One can be easily frustrated with Siri if your contact list consists of hard to pronounce names. The workaround is to set phonetic first or last name fields for your contacts.
This isn’t new, but now that Siri is relevant on the iPhone 4S, it’s probably one of the more important tweaks to maximize your Siri experience.
How to set a phonetic first or last name? Just edit your contact, tap ‘add field’, and select them. Then, add any phonetic spelling you wish. Do you know how to pronounce a name like ‘Eoin’?