Perfect for the price.
Lot of data (with version 1.4 now OSM datas), fast with t2.medium server and great email support.

The price is acceptable but the data is not complete. What I need is zipcode, that simple. But document shows if need zipcode, I can only access their website, and the price is unacceptable.

I used it as a free trial while researching solution for a simple reverse geocoder (We only need city level info for our purposes)
This is a strong possibility for us to use once we have the other pieces in place.
I wish they provided better documentation though. For example, it does not mention anywhere that you can call the API using a geocode or geonumber, and adding a '.json' to a request gives json output on any request. Neat features, but one has to find out on their own.
(There is a README file and a test script in the ec2-user home dir after you ssh into the box, which just states:
"Copy test.pl on your machine then replace 'localhost' with the ip address or hostname of the reverse geocoding machine.

Then run ' perl test.pl '

You should get around 100 requests per second if the software is running on a t2.micro instance (the minimum instance)

(Higher instance types get better throughput)
"
What it does not say, is that running test.pl locally, causes the machine to run out of memory (Granted this is only a T2.micro with 1G of RAM)

Overall it is solid when accessed externally.