A couple days ago i switched to a Galaxy s5, same number. I have no problem sending any short texts but over half the time i send a longer text (around 100 characters plus) the message will not be received.
I would follow Highrisedrifter's advice and check out Android Central. The one thing I can tell you is that I know Android texts (long ones) will come through in multiple texts based on character count...and most of the time they will come in backwards. For example, one long text on your end (Android) may be broken un into three smaller texts on the other person's phone...and it will say (1/3) (2/3) (3/3), with (3/3) being the first one received.