Given reviews from Amazon, classify those review based on their content into two classes: Negative or Positive.

[EX Q]: I received the product in a timely manner. It was as advertised. I have used it a number of times and it works well although I haven't gotten the results from it I had hoped for. No fault of the seller or the product though.
[EX A]: Positive

[EX Q]: I was surprised to see that the item was used. Advertised as new. Would have liked the new ones stead got used.
[EX A]: Negative

[EX Q]: I bought this because it was a cheaper alternative to Mac's (ridiculously priced)$80 charger. At first it worked pretty good, but about a week or two after i got it it seems to not be working like it should. i think there is some kind of warranty, so i should try and exchange it...but sometimes when it is plugged into my computer it will charge for one second, then stop for one second, charge for one second, stop for one second, etc. It still manages to charge the computer, but im not sure if all this on\off stuff is necessarily good for my computer...
[EX A]:
Negative