I think stating it that way trivializes the amount of work that _has_ gone into lambdas.
There's been a lot of other, more fundamental things discussed over that 2-3 year period about their implementation; way more than syntax.
Do you mean about how lambdas are implemented from a bytecode standpoint, or other types of issues?
For instance, there was a long battle over whether () would be enough to invoke a lambda, or whether some sort of apply() or invoke() or .() method would be required, and a lot of the problems with () come down to differences between the way fields and methods are inherited in Java, esp. w.r.t. shadowing. I don't even know how it all came down, but it gets nasty, a lot of this stuff just wasn't designed with lambdas in mind.