Agree with some of the comments here, it CAN be a huge CPU / memory hog but if its used properly then the resource problem can be minimised. For people like me its a cracking tool and what has been promised in the upcoming version 5 may make everything a lot easier.
Like most programming, there is a steep learning curve but once you have the basics mastered you are sorted. THere are some great plugins being built by people that you can by to make a few things a bit easier but you don't have to buy them.
I have been using it since it first came out and although there have been rocky patches in terms of support and company direction, I think (well, hope) that will all change when Version 5 is launched.
Summary - I have the dev version and its made my money back multiple times over and I can now get a basic bot out of the door in an hour. It does what it says on the tin and, again in my opinion, it is much better than other automation products on the market.