Pages for the iPad and Pages for Mac are both excellent, but are different. I have them on my Macs and my phone...Will be on my new iPad when it arrives tomorrow.
I find it's pretty hard to use seriously on my phone, I just tend to copy stuff from emails like invoices or order confirmations if I get them when I'm out.
On my ipad2, it was great...very useable WP DTP package. The Mac version is much more of a MS Word competitor though..I have both...Office for Mac was a must...Wish I didn't have to have it, but I prefer Pages "No nonsense" look and feel.
Can't remember what I paid for the iPad version...I think it was around £12 so probably about $10 since we always pay double in the UK It's worth the money though.