the only good thing about having nexus 5 on metro is that you do not need to root your phone and apply settings.db hack with user agent switcher as you have to do for all other carriers. even though we use t-mobile towers but as our signal passes through fast.metropcs.com apn ...voila!!
i could not believe it myself at first! there is a catch of using the switcher, it makes your browser act as a mobile browser or like a google/bing/safari bot. so you do not get full functionality of a web page has to offer.
there is a data speed shaping on metro if you use more than 1 GB data a day (at least for me). speed resumes as normal next day.