We've been using F5 big-ip LTM's for more than 10 years, The best part is iRules - easy to write, mange and route/block traffic. The new version of LTM's has cool feature of IRule editor in GUI, makes more easy for any changes.
Great platform i have ever seen in the market
Support costs and renewals are expensive, but it is worth of it because of great features and performance that F5 has
As a webinar company, we are using F5 for our steaming and platform application services, works very great.