My wife and I have had this conversation several times!
We both really want to like the 500L, but sadly it's just not for us. We test drove one a few years back, the basic 1.4 engine was fine to be honest, but it did feel quite hefty and large and the gearstick position was an issue for my wife in particular.
Other than that, it's just a bit too much of a weird mish-mash - think that's partly because we've owned a 500, Panda and Punto and you can clearly see all the individual bits inspired by those cars! But you're quite right that the second hand 500L market is very attractive price wise.