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

Input:
This is a great unit for the first few months.  It does in fact seem to be one of the more powerful units out there.  But I've owned several of these and have noticed that the rechargeable batteries begin to lose their power after you've owned it for awhile.  The vacuum starts out at full power but this only last for about 10 seconds, then the motor quickly winds down to almost nothing.  This is too bad because it is a great machine otherwise.  I would recommend against buying a B & D.

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