_Utilitarianism_ is, despite the train-wreck of the fourth chapter, one of the clearest expositions of ethical theory ever written. Anyone interested in ethics in general, or utilitarianism in particular, should be familiar with it. But then, you already knew that.
As far as specifics regarding this edition: It is offered without introduction, conclusion, analytical remarks, historical context, or any of the other chaff that tends to build up around great texts. I find this refreshing; some may find it disappointing. Unfortunately, like all the books I've ever bought from the Prometheus press, it is very poorly bound. On the other hand, because this little volume is so slim (<100 pages), it is at lesser risk of falling apart, or loosing pages.
If you want to read Mill in a solid, cheap edition, this copy is perfect. If you want an edition that will not crumble to powder within the next 60 years, look elsewhere.