Mostly, all you have to do is look at it. Does this look okay?
![enter image description here](https://cdn.statically.io/img/i.sstatic.net/r8Ayv.jpg)
I don't think that looks great for the poly count myself. But, the issue is much the shape as the topo. I've separated out a cross section so you can see that the shape isn't as smooth as it could be, even disregarding topology. (Generally, using as few vertices as possible is the ideal way to get the smoothest geometry, and I'd say that this neck has more vertices than it needs to provide the level of detail that it's going for.)
Now, animation can complicate things, so if this happens to be good enough for you, will it still be good enough once you rig it? Your topology needs to be good enough to support the deformations you want-- if something is smooth at rest but is going to deformed into a ridge, you still want edge flow that supports that ridge; if a star is planar at rest, it's still going to be a problem if it gets deformed out of plane by your armature. But in the case of Rigify, it doesn't really do anything with the neck tendons, so overall, deformation with Rigify alone isn't going to make this any worse than it is at rest. So if the rest mesh is good enough for you, the Rigify version should be as well.