At the moment there are many limitations.
There isn't one solution that I have seen so far that does best in every perspective of trading technical analysis. However, for each perspective, there are clear leaders that provides free or very cheap services.
For technical analysis I usually have to jump between these sites, which is acceptable except that the programmetical strategy in QuantConnect only supports C#. As a professional Java engineer, even with strong motivation to code my strategy, I couldn't get started with QuantConnect. Therefore the short-term goal of OmniTA is to provide minimal charting, back testing and a programmtical strategy definition functions just enough to build strategy in Java and test. In additional to that, I'm planning to provide the service for free to majority of users.