It's not a sports car, crotch rocket, luxury roadster, grand tourer, or anything else. It's a tall Mazda3 with sliding doors and a couple hundred more pounds. It uses the same engine, same transmissions, and same suspension tuning as the 3 sedan and hatchback (which is why it's softer and leans more - same suspension, more weight). I often say it's the wagon-minivan version of the 3, because it essentially is. The 3 is an inexpensive, compact car and the 5 is an inexpensive, compact car with sliding doors. It's more fun to drive than other minivans and most wagons, including everything in its class (that there is). I didn't cross-shop the 5 with a Mercedes SLK, a Jeep Grand Cherokee, or even a Nissan Maxima, because they're not what the 5 is about.
Do you want the ability to carry two people and a massive amount of cargo OR four people and a moderate amount of cargo OR six people in a pinch - all in a compact-car footprint?
Do you want a low entry and running cost?
Do you want something that is fun to drive for what it is?
It doesn't get great gas mileage. It's not quiet on the highway. It's not super comfortable for tall or wide drivers (because it was designed for the Japanese market). It can't tow. It doesn't have AWD. It doesn't have a lot of horsepower. It has Mazda's paint and rust problems. Many of its components are Ford Motor Company.
So what? It's a class of vehicle that was popular in Europe and East Asia that Mazda tested to see if it would take hold in the U.S. & Canada. They spent almost no money marketing it or otherwise modifying it for the tastes of North Americans because it was a gamble anyone at all would want it. But it also cost them almost nothing to make it for us since it shares so many parts with the 3. The lack of improvements to the 5 certainly didn't help its case here, but you only need to look at the market for these miniature vans in Europe and Japan to see that the failure of the 5 in North America isn't an isolated case. People around the world just aren't buying these vehicles like they did.
I like my 5. I would like to change some things about it, but I'm happy with it, and I knew what I was getting into.