I can't address worldwide travel, as I have not taken my phone beyond the United States and Canada.
I know that many people here don't like Sprint PCS, but I think that for the money, they are the best deal around.
I pay just under $39 per month (taxes included). For that, I get:
500 Anytime minutes
1500 Night and Weekend minutes (8pm to 7am)
500 PCS to PCS minutes
I have had this plan for about a year. I think Nights and Weekends for new users begins now at 9pm, but I talked with a representative from Sprint who thinks the company will change it back to 8pm when the new plans are released later in February. Apparently, users aren't happy about all providers cutting back on off-peak minutes.
Also, the plan I have normally goes for $49.99, but through my (former) employer, I have a "volume discount."
In the 2.5 years I've been with Sprint, and in all the cities I've been to flyinf with Comair, I've NEVER had to ROAM. There is an occasional dropped call, but to call it anything more than occasional would be overstating the problem. Certainly, there are no more dropped calls than what I've experienced with Airtouch, Verizon, Cellular One. Sprint does not have service in Canada.
Also, I spoke with a Sprint rep last month who said later this summer, Sprint is supposed to release some kind of modem for laptops that has such a high transfer rate it will put RoadRunner internet service to shame. Maybe he was just hyping it up, but that's what he said.