I have a Quiny Buzz - had it for 20 months and used it a LOT.
Hmm. I'm not terribly thrilled with it at the mo, but I've never had another pushchair, so it may be a case of the grass being greener.
On the plus side you can get the dreami carrycot attachment for a newborn (which we did and loved and will use again for the new baby when it arrives) and it also fits the maxi cosi carseat.
Another huge plus (and what made me get it in the first place) is that you can have LO facing you when she's tiny and then facing out when the big wide world becomes more exciting than mummy. I loved that about it.
It has also taken a real battering with us and survived. I take it running (not always on smooth paths) and am always off-roading while walking the dog.
Now for the bits that I don't like:
I've never thought that dd looked as comfy or cosy in her pushchair as some of her friends. It's a bit exposed and wipe-clean.
The rain cover is not attached in any way and the only place to keep it is in the underneath bag which leaves you nowhere to put your shopping or other stuff. Also it has one handle, not two so you can't hang carrier bags on the handles. You can put a change bag or a normal bag with a BIG strap over the handle but it's not ideal. (Although, to be fair, you can get an underneath basket attachment which I never got around to - perhaps I should have done rather than moaning!)
The wheels are very very wide. This is great when in the park but is a pain when shopping in town.
It's very heavy and bulky. Not a problem to us as DP and I are both fit and have large cars. Might not suit everyone.
I feel a bit negative about it now, but for most of the time I've used it it's done me fine.