People say that is easy to understand spanish, but it's not so simple.
If a brazilian person talked with a spanish speaker, they will manage to communicate easily. Because, they would talk as slowly as possible knowing that they don't speak the language of each other.
However, if a brazilian listened to a conversation between two spanish speakers. He/she would be in trouble. He/she would break his/her back trying to get the conversation. Because, in this case, the spanish speakers would talk naturaly (in other words, very fast).
But yes, spanish speakers and portuguese speakers don't need to break their back to communicate to each other.
I hope I've been clear. :)