Postby 法月 » December 30th, 2006 2:29 am
「わたし」 is the formal form of "I." It can be used, and is used by both males and females. However, it is also common for males to use other forms of "I", such as 「ぼく」 and 「オレ」. Therefore, it seems a lot more common to see females using 「わたし」 than males---this was probably what gave your friend the impression that only females use 「わたし」. To clarify:
私(わたし): Typically formal, can be used by both males and females
私(わたくし): Highly formal, typically used to speak to a person of higher rank
僕(ぼく): Informal, Typically used by younger males, but sometimes is used by older males too
俺(オレ): Informal, typically used amongst friends, masculine.
あたし: Only used by females; informal.