For an unspecified limited time, customers activating a new line on MetroPCS' $50 month plan get 8 GB of high speed data instead of the usual 5 GB. It's not clear if current $50 plan customers will get 8 GB or not.
In addition to 8 GB of high speed data, the $50 plan includes unlimited domestic calling and messaging and unlimited 128 Kbps throttled data after the first 8 GB. The plan also includes Music Unlimited which zero rates streaming music from over 40 services including Apple Music, Pandora, iHeartRadio, Napster and Spotify. That means that screaming from those services does not count against the plan's 8 GB of high speed data.
If you need more lines, up to four additional 8 GB lines can be added for $30/month each. The first line must be on the the $50 plan. That means that two lines cost $80/month, three lines $110/ month, four lines $140/month and five lines are $170 per month.
This new promotion replaces MetroPCS' previous offer of two lines on $50 5 GB plan for $75 per month, three lines for $100, four lines for $125, five lines for $150. That promo was available in stores only. It looks like the new one may be available online. There's no indication on the page on Metro's website announcing the promo that it's in store only.