HP Network Automation
I give HP Network Automation 5 stars, maybe 7 - yes, I know it is that good!
Clients are always excited to be able to easily push out changes and ensure that all configurations are in-line to the defined standards via the audit function and built-in reporting.
There are bugs to work through along the way.
Deployment is quite simple. Scalability has not been a problem. Stability has only been a problem when I have exceeded vendor recommendations and not made recommended system changes.
Cisco Ciscoworks. Most companies have had this and replace it with HP Network Automation as it is very easy for users to work with and can handle a heterogeneous environment easily.
It is on par or better than other vendors support. They have really made an effort to improve and are working hard to deliver great support on every level.
It's rather simple. Adding in gateways can be a bit complex, but not too bad.
I've done both - first with vendor, then after that it's been in-house.
Make sure your network team(s) is / are aware of the work you will be doing, as you will need their help (firewall rules, credentials, etc). Work with the engineers and ensure they able to fully take advantage of the power of Network Automation.