Boston Dynamics has wowed the world with its series of two and four-legged robots, but one analyst said Wednesday they are yet to become the military's best friend.

Last month, a sneak preview of the firm's upgraded SpotMini robot was released. The short video showcased its new color scheme, angular movement and prancing style.

SpotMini is the latest evolution in Boston Dynamics' family of ambulatory (walking) robots that started with the BigDog system, developed with support from DARPA (Defense Advanced Research Projects Agency) and the U.S. Marine Corps.

The U.S. military is leading the charge on ground robotics as it looks to produce an unmanned vehicle that can accompany troops moving on foot.

But Huw Williams, editor of Jane's International Defence Review magazine, told CNBC by email Wednesday that the reception from the army has been mixed.

"They can operate in a lot of terrain, but don't have the mobility to go everywhere," he said. "Their noise signature is an issue – battery technology isn't where it needs to be to meet the power requirements of larger systems, so they have been powered by traditional combustion engines, which are noisy."