Hmm... I'd like to put forward my opinion on this matter, and for this purpose I would like to cite V/H/S 2. One of the shorts is practically this, except done in a film format. Therefore, I would like to venture to say that it is possible to write it in such a way that it is both realistic and fun, and there are two ways in theory to do this:
1) The zombie that used to be a character would have a rather short lifespan as it rises in a situation where it would be killed quickly by other PCs or NPCs. Alot of writing could be dedicated to how much was lost due to the PC's death and return as a zombie, what tragedy is there and of course, it could be used to provoke writing related to the zombie.
2) The zombie that used to be a character 'lives' for a long while. In this case, it would usually have a very special purpose. For example, it might prove to be a severe hindrance to other PC or NPC survivors (especially in the case of those rare dangerous type zombies), or even the cause of death and reawakening. Most of the writing would be similar to the above, except with the added bonus of the possibility that it could encounter other survivors not of the PC group, who are inconsequential and can be killed for various drama and such.
In both cases, I think it's just a matter of how you write it I suppose.