The Kirby, in my opinion, is a very good vacuum cleaner - but not worth the asking price new, nor do I like the selling technique.
I got one off ebay and it cost me £110, and its about 10 years old.
Some say they are too heavy - I think they are about the weight of a Dyson, perhaps a bit more but not much.
They can be difficult to push and pull if you get the "wrong" model.
Mine, and remember its 10 years old, has a foot operated switch that operates a drive so pushing and pulling becomes as light as a feather.
Good beater bar on the Kirbys, better I think then the Sebo BS36.
Downside I find is that to convert to be able to use a hand hose/brush is too fiddly.
Buy one second hand in good nik with the power drive for £100 or thereabouts.