I used both GMaps on a GSM Galaxy Nexus (Jelly Bean) side by side with AMaps on a AT&T 4S all weekend.
AMaps has so much POTENTIAL, but like others have said, the problem is not with the UI (although, I would love to see a "estimated time to arrival"), but with the meta data.
Google and GMaps have GOBS of meta data for every location you can think of. For example, let's say I work at Lowes. On AMaps, I type Lowes and it comes up with a few listings, but none of which is the Lowes I work at... this Lowes has been here for 15+ years. Oddly enough, this Lowes also shows up on my ol 2004 TomTom, which is one of the sources of AMap data... On GMaps, I type "Lowes" and it routes me directly to the front door, complete with street view picture! The Google Now voice is much more human and natural sounding than robot Siri. Although, Siri ACTS more human
Like many (many, many) have said, it will get better. It's just a shame that they had to take away what they already had in place to give us a near-beta experience.
My advice for those not liking AMaps for whatever reason, give Waze a shot. It's free and comes with neat features, like cop alerts, weather alerts, traffic alerts. See an issue with Waze? Go to your computer and fix it! Fix it once and it fixes it for everyone.