GridGain, the commercial company behind Ignite, and the community seem to be implementing the features correctly so that they work as advertised, backed up by the case studies and personal accounts I've heard.
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.
