I own a 2010 Mazda 5 - because we needed another car and Mazda are doing pretty good deals to get rid of the last before the all new 2012 is available in February!
We purchased the car because we need a car that can seat 4 adults and has room in the back for dog + stuff, but we also needed to occasionally flip the seats for one or two young kids (but no stuff). Eventually my wife and I will have one or two kids, a dog and stuff - if the kids have friends along there probably won't be a dog, or as much stuff - so the limited cargo room makes sense. This won't work for everyone, but the seating arrangements are perfect for us.
My critisims of the current car are the 5 speed manual needing a 6th gear - fixed in the new one. The current 5 speed auto needs another ratio though as well, 1st, 2nd and 3rd are lowish to make it nippy in town, but 4th and 5th are a little high - a 6th could slot in and allow 4th and 5th to be closer ratio.
My other critism most revolves around road noise - I owned Hondas before, so I'm used to it, but apparently they've made the 2012 a lot quieter, which is exactly what it needs.
In terms of the 2012 I'm slightly disappointed - the 2.5 is barely more powerful (though more torque) and I really think they have missed a trick by not pulling in their new direct injection 2.0 which has almost identical figures to the 2.5 for power/torque, but is significantly better on fuel. They also need a 6 speed automatic to compete with the larger minivans on highway economy (a 2011 Honda Odessey is theoretically better than the Mazda 5).
A poster mentioned front leg room - I was surprised that I fit - it seems tight, but the seating position works. I'm tall and with stupidly long legs for my height - when I saw the driving position and I didn't think I'd fit, let alone be comfortable. It's worth trying out.
As a vehicle I love the Mazda 5 and the whole concept. It's light, fun to drive, economical and mostly fast enough. It's easy to park, it has enough space and it's not a hulking great minivan with a 3.5v6!
Every month I drive myself and two or three collegues for a few hours to a different part of the Province - they love it. They all have armrests - enough legroom, large windows, easy access (especially the middle row!) and it rides well. It's certainly not a "cool" vehicle, but a lot of my age group (somewhere from mid-20s to mid-30s) really like this car, which surprised me. Even my 21 year old brother-in-law wasn't as scathing as expected!