I have two, a 901 and two 510s. I don't have any problems with my blu except its small cartridge and short battery life. I love the PCC. I average about an hour a battery on the blu, but then, I only get 2 hours from the 510's.
The 901 battery seemed to last a bit longer... maybe 3 hours for me, but I hate the hole in the atty where you can so easily cover it, the inconsistent draw, the carts sticking to the atty ( yes, I was topping them constantly - nothing worked), the shut off and the fact that I blew an atomizer in days, the batteries were degrading in less than two weeks and the supplier has yet to get back to me.
I am in LOVE with my 510s. Even with their short battery life, they are the closest to perfect I've experienced yet as far as machinery. When I have a bad cigarette moment (It's been 2 weeks now since the last one) I get out the blu and go outside. It *feels* the most like an analog in my hand - and that helps. So I suppose it has its place in my collection
Next up - the Janty Stick... with 510 attys I think it might be bliss