SEO stuff
I wouldn't think it would harm anything…
The crawlers out there really do not care about arguments, as long as the page is there and it is accessible, it should be ok.
site crawlers do not guess directorys / file names. If you link to it, it will take it.
On the other hand, I think it looks bad. I personally do not like paging things as you stated.
One simple reason for this is say someone comes to your site… www.somesite.com they do not know your pages are set up via arguments and can only be viewed via arguments.
So say you have a registration script on your site, they will look at the URL and see http://www.somesite.com/ and say they want to register, they might not look for a link to the registration rather just take a good guess such as /register.php but really you have it set up as ?page=register
Hope you notice what I am talking about, but what you are doing should not effect your rank / indexing
Another good idea would read up on how crawlers work. For example: http://www.googleguide.com/google_works.html