Instruction: Given the user's review, identify the user's sentiment from the listed options. Answer using one of the options.

Input:
At first I was extremely satisfied with the purchase of this tumbler. However, little did I know what was growing in the little crevices of this deceptively clean and sleek looking mug...
If you don't put milk in your coffee and tea then this is probably the travel mug for you. It keeps drinks cold or hot for hours.
BUT...after just a few weeks of drinking my coffee and cream, I realized how hard it was to clean this mug. It has so many little corners that are IMPOSSIBLE to get to. (I don't understand why someone can't make a travel mug that you can take apart completely to wash thoroughly.) Basically, I had to resort to jabbing knives and forks into these corners to remove the gunk (probably from the fatty content of milk) that quickly started to infiltrate. There is this rubber ring towards the top of the inside of the mug that has a small gap on the underside. If you have one of these mugs but never thought to look under it, I warn you...you will never look at your mug the same way again. I finally decided to rip off the rubber ring, and the contents were disturbing...milky, brown, jelly looking gunk. It was a horrible moment... I dare you to buy this mug, drink from it for a few weeks and then be brave enough to peer into the dark corners of your pure (so you think) java utopia....

Options:
A: very positive
B: positive
C: neutral
D: negative
E: very negative
Answer: C: neutral