I'd se we enjoyed the penguins near Cape Town more than at Phillip Island. Neither compares to the Antarctica, though..

At Phillip Island there's a lot of people you don't really get much more than see the penguins in dark when you go on your own. If possible, try to book one of the premium tours. We upgraded our ordinary tickets to "private penguin parade experience" when we noticed they had them, much better viewing options and you learn much more from the local guides.

On our travels we've learnt that it is always worth checking the private / premium options. Often for a little bit more money you get much more personal, detailed and memorable experience.