Juniper NetsScreen is a pretty straightforward firewall appliance which is certainly a good fit from mid-size organizations, to big enterprises (a lot of varieties are available). However, NetScreen is going to be EOL by 2018 per my latest knowledge.
There are a few useful features in NetScreen, which makes the life easy for a firewall administrator i.e. packet debugging, packet handshake visibility, VPN configuration, integration with central management server etc.
It has provided reasonable firewall level security to the IT networks.