Which Vacuum Should I Buy? Dyson vs Shark

I have a new apartment.

That means a bunch of stuff was needed to fill it up and make the space livable/enjoyable.
I've bought a couch, bed, some furniture, kitchen stuff, etc.

To keep the space clean, I will need a vacuum.

So in making that decision, I need the interweb's help:

Should I buy a Dyson or a Shark?

The Dyson is... well... a Dyson. But it costs $400.
The Shark uses similar technology and only costs $150, but doesn't have the same reputation.

So what does everyone think?

Update: Today on Woot!, there was a deal for a refurbished Dyson DC25 for only $250.

So I bought one.

Thanks for all your input!