General

I know that GSM is used more often world wide (especially in europe). Are there any technical advantages to one system or the other (superior sound, coverage, e-mail, internet access, IM, etc?)? Is one system fading out over time? Are certain phone technologies limited to just one type? If so, which have generally been deemed the most important (one system features)? If there are no major technical advantages to one system over the other is it just a matter of choosing whatever one works best in the areas you are most likely to frequent? Are there general price differences or are those mostly due to Carriers and not the broadcast technology?