There are some limitations, apart from them, the smartwatch does everything when paired to a Nexus 5 that it does with a Samsung device. The obvious limitation includes unavailability of S Voice and Weather, all other functions appear to work just fine. Those who are willing to try this out on their own would need to first install the Gear Manager app on their Nexus 5, and then install a few other APKs which are needed for this hack to function.
It is not known at this point in time if this hack can make the Galaxy Gear work with other Nexus devices, such as the Nexus 4 or the Nexus 7 tablet. This hack really only helps someone who already has a Galaxy Gear, people using it on a daily basis are bound to have a compatible Samsung smartphone as well. If you use a Nexus 5 and are able to borrow a Galaxy Gear from someone just for the heck of it, then you can follow the installation instructions given here.