Cons: There seems to be a lot of issues with their back end server infrastructure and cache updates. Elements and page orders, etc. do not always update as you expect them to, as well as their server systems have proven to be only about 90% reliable. Not a problem at low traffic volumes, but a huge issue for anyone driving thousands of users per hour to their sites. Support is also not that knowledgable or helpful, though they try their best.

Overall: I tried to use it for 6-8 months, I am located in Costa Rica (Central America), and there are a lot of restrictions mainly with currency. It looks like it works fine with the integration of Stripe because you can do upgrades, sidegrades and downgrades, however if I am not mistaken, it only works in USA. In my case, only Paypal works and is very limited.
Testing can be conducted sequentially or in parallel. In sequential testing, often the easiest to implement, the various versions of the webpages are made available online for a specified time period. In parallel (split) testing, both versions are made available, and the traffic is divided between the two. The results of sequential split testing can be skewed by differing time periods and traffic patterns in which the different tests are run.
Steps in Sales Funnel – This lays out for you, point-by-point, each page and step the customer goes through on their way to making a purchase. In some cases, it also works to point out some of the follow-up steps and “if-then” scenarios. For instance, how does the funnel respond “intelligently” to get prospects who didn’t buy to come back to the website?

Clickfunnels: Review, Demo, Pricing and Features: