I don't have a Blitz. Recently bought a semi auto Invader and I can say it's definitely an okay gun. I sold it though & will never buy another one new.
I'm not a complete AG snob so I won't say they don't work. They work great and mine was astonishingly accurate.
I'm just enticed by a little more refinement in my AG's and I look at build quality, longevity, ease of maintenance. I'd rather have a tuned spring gun over a high power Hatsan but they're absolutely great if all you want is a kind of hokey looking AG with gobs of power to send pellets or slugs screaming.