Google held a showcase today to show off Stadia ahead of E3 and with the full list of confirmed games, a confirmed price for $9.99 a month, and more, it looks to be a very impressive service. That being said, hope you don't have a data cap because you are going to blow right past it.
According to the most recent Stadia showcase, this service offers a 60fps 4K stream at 35Mbps. The above graphic shows off the recommended minimum and the "best" specs for speed and resolutions, which was about what was first teased back in GDC earlier this year. That being said, for those that have limited date this definitely poses a problem because as our friends over at PC Gamer pointed out, 1080p60 comes out to about 113 hours of streaming each month assuming that internet service aren't being used for anything else.
Of course there are lower resolution options, but the main appeal of Stadia is 4K support. Without that, there's really not much of a point to it other than just being another option with a bit more of a tailored experience.