Used Ignite on two projects. Was a good match for one, was a poor match for another (not Ignite's fault - poor choice at project outset - did not match initial team's skills or project requirements). In both cases was very impressed with Ignite's docs and community. It works pretty much as advertised/documented - and the GridGain guys really know their stuff. The commercial version - GridGain - has some nicer tooling/ UI capabilities and support - if you have the budget, otherwise the Apache project is solid to build on and well documented.