We considered a Prius V at one point before getting a Mazda 5 but a few things made it a no go from the start - for comparable 2012s there is a 7-10k up front price premium for the Prius, that's a lot to make up in potential gas savings, even considering vehicle value in 6-8 years; the Mazda 5 is incredibly practical with the sliding doors, seating for 6 and rear storage area, an area the Prius couldn't touch when considering the needs of a small family; and ultimately the Mazda 5 is simply just more fun to drive. My wife is really not a car person at all and the Prius was the only car of the many we test drove where she commented it was boring and plain.
Thus far we have been very happy with the 2012 Mazda 5. Almost 60000 Kms, everything still original and no issues noted or in need of repair, suspension or otherwise. It is geared much better for highway cruising than my Mazda 3 so hopefully get similar or better mileage even with the added weight. The 2.5L seems very adequate even when fully loaded, ie recent camping trip with 4 and all the gear, cruising happily at 120-130kmh.