Perfectly adequate for my needs. Possibly perfect for your needs as well.
Two bucks gets one where one needs to go (some people pay nothing; they just hop on [it is considered "fair pay"]).
There are a lot of rules, and, there are employees/guards who come by at times to swipe transit passes (making sure everything is on the up-and-up) on this small hand-held devices they carry. At this point, you may want to make this your "stop," if you still can, as I have seen others do, so you do not get issued a costly citation.
The Metro is connected to PHX airport via the (free) Sky Train™ (before, one had to ride a shuttle, provided by Metro Light Rail [free]).
I ride it every time I am in Phoenix. Wish we had something like this in Vegas but we probably never will. - E