Sure - competition can result in higher prices and/or lower quality especially when it isn't properly regulated.
One reason for this is that people make choices to beat their competition rather than to provide for their customers. Often short term thinking leads to quality losses in order to capture market share and sometimes the competition devolves into direct sabotage of competitors. This intense competition can result in higher costs for consumers as it becomes more difficult to bring products to market.
Even without that, you can have price competition which, while theoretically leading to a low cost for consumer in the short term, can price out high quality goods in a price conscious market.
Flooding the market with cheap, low quality goods can lead to overall quality drop and a decrease in investment in the area. Even though consumers prioritize cost over quality when given the option in some markets, it doesn't necessarily mean they are making the correct decision.
The same thing could just as well happen with a monopoly, though. Look at ISPs injecting ads and fiddling with DNS, for example. There's very little competition in the US ISP market, but plenty of players are still eagerly seeking bottoms.
