On the whole Metro is a decent value. In Staten Island and have the a grandfathered unlimited data plan. The Esteem which was far cheaper when I got it has been a pretty good phone that runs any android app I throw at it.
Voice quality is fine. Not as good as Sprint. But better than T-mobile when I had that.
Coverage in Staten Island is pretty good. Though I do reach dead spots when visiting Brooklyn. Sometimes indoors I get 1x rather than 4g. Pandora can still stream pretty well even at 1x. You'd want 4g for netflix however.
Speeds are adequate. I'm not downloading huge files or anything. As long as I can stream without buffering I'm fine. Anything huge I can get at home on my FIOS connection.
What is killing Metro right now is probably pricing. Virgin/Boost/Straight Talk offer more for less. At least on paper. The Evo on Virgin is a better value than an Esteem on MetroPCS. It's a better phone, cheaper, and costs less per month.
And with Straight Talk you can get a vastly superior Google Nexus and pay only $45 a month.