Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Good at first but....

I loved this Waterpik at first because I'm limited on counter space and it seemed the perfect solution. However, after about 8 months of using it I wish I would've bought the plug-in version. Just like many other reviewers I find that the thing will not hold a charge for very long. You might not think it's a big deal to recharge it but a full charge delivers the full amount of pressure and the correct jet pressure delivers the results you're after. My dentist just told me that my gums don't look as good as they did 3 months ago because my Waterpik is ineffective unless fully charged. Sooooo.... I will be researching a better quality unit and would caution anyone who's thinking of purchasing this.