I disagree. I create websites primarliy using .NET technologies, but I think PhpNuke is a great tool for web development beginners. That's how I started and I'm pleased with where it has taken me.
With a little bit of creativity, and if you can learn the basics of PHP and HTML, you can make PhpNuke customizable just the way you want it.
PhpNuke is just a framework--a starting point for developers. You can do everything with it that you can do without it. It doesn't limit you in anyway.