I have been vaping since mid-April and have tried the 510, 401, and 901, so herein lies my very humble and novice opinion of the DSE 901.
I love the DSE 901, with the exception of the short battery life, but there are some pretty spectacular fixes for this small issue. This three piece model hits well, produces great vapor and flavor, and is easy enough to maintain.
I love the whistle tip carts along with the atomizer.
The carts are really easy to work with, as you can easily grasp the carter filler with a pair of tweezrs or paperclip. This makes washing and refilling your cart material simple - I still struggle with the 401 carts. There is also a cart mod that you can add, which has completely eliminated my need for a syringe to correctly refill the cart with juice.
Learning to use it correctly is of the utmost importance - like Royal pointed out earlier - do not drip on the atty because you might mess up an auto or unsealed style battery.
The atomizer is easy to maintain and consists of simply blowing out your atty every evening and draining it cart side down on a paper towel. This is all I have ever done and I am still on the same atty I started with back in April.
You also need to wash out the cart filler and plastic cart with hot water every few days, this will help maintain a germ free environment. I even soak my plastic carts (no cart filler) in some hot, soapy water for a few minutes, rinse and dry. IMO this step should be done with all PV carts, with the exception of the cartomizers (you'd kill it for sure).
This atty and cart are my choice and since they have many battery mod choices, I have found my vaping nirvana!!

IMO the DSE 901 is among the best out there for anyone just starting out.
I am sure that I missed something, so please feel free to add anything!
mamacat
