It's not bad for a small yard. I have one mainly because a neighbor was moving so I bought it brand new for $50 on a whim, but I also I have a small yard and already own a corded trimmer. If I were starting from scratch I'd go with battery unless money is a limiting factor because in the end corded stuff is dirt cheap.
I've used gas and corded in the past, and yes you have to move the cord sometimes but usually you can establish a mowing pattern that only requires you to do so a couple times. And when I do need to move a cord I just grab it and flip it over the mower like a jump rope and then I'm back mowing within a couple seconds.
It's nice not ever having to think about battery life or gasoline levels, but if our yard was much bigger I'd 100% go battery because once the cord is long enough it is definitely a pain and gets impractical.