I guess - as with everything - it depends on how you're using it. I've seen an amazing routine with just a normal pen

That said, it's nicely made and relatively easy to use and there are a whole lot of uses depending how far you can stretch your imagination. If you're doing the pen through bill, it's a little tricky to get everything in the right position - but nothing that can't be overcome with a bit of practice.
It's a nicely visual effect in that they think they see the pen going through the bill - if that's what you're using it for.
I've found that people think they've figured it out (and they're usually right), but they usually rule that out when you let them examine the pen afterwards. The reaction is "well it looks like a normal pen.....*some or other exclamation*..it is a normal pen

It's not something I use all the time - but every now and then. It could be cos I'm not 100% happy about the way I handle it yet.
Hope that helps..