This idea that food goes `off` in the freezer is so obviously a complete load of nonsense that I`m surprised that it crops up so often. If the food was contaminated before going in, then it would be unsafe after days let alone months. There is no reason at all why it should be a health risk after a few years, BUT quite likely, the older it is, the more tastless it will be and consequently may be a bit of a disappointment if entertaing.
Having just got a new freezer myself (this time an upright) and having to transfer the contents the the old freezer in the shed, I found a few things from around the last century but they`ve been eaten.