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.”

Williams said the new SpotMini goes some way to addressing these issues, especially as its smaller battery pack reduces noise.

But the defense analyst said it’s unclear if the military could find a use for it.

“Its size precludes it from carrying a significant load and it will likely have limited endurance at this stage,” he said. “Advances in battery tech will be a key determining factor in the success of these types of system.”

Williams said there could still yet be a role in security tasks, such as patrolling bases and investigating potential threats or acting as an advanced scout for ground troops.

He said unmanned, larger-wheeled vehicles are another U.S. military ambition as they could operate as personnel transporters or medical evacuation.

Williams added that the ultimate goal of the U.S. military is to produce a “networked battlefield” with land and air resources supporting each other.