Yes, it's normal. I would be shocked if there was ever a grad student in the history of grad school who did not at one point hate their job. I'd be shocked because it would be living proof that aliens exist and walk among us.
Of course, if you want to be tenured professor at Harvard (or, say, Max Planck - let me not be chauvinistic) and thrice Nobel laureate, it sucks to not have a hot topic. Although, consider how a topic becomes "hot" in the first place: A very talented scientist makes a fascinating discovery, and everyone wants to get a piece of the action. Fields are not "hot". Good research makes them hot.
Even if it does turn out as bad as you think, there is more to a PhD than being an academic rockstar and publishing the "next big paper". If you can finish your PhD, it proves that:
- You were disciplined enough to go through several years of independent hard work
- You could manage your time and the direction of your project effectively
- You are an expert in that field (even if your original research is unexciting, it doesn't mean that you don't have very good knowledge of existing research)
- You are smart, capable, have good critical thinking skills and so on
These may seem like boring, second rate consolation prizes, but if you think about it in perspective, there are very few people in the general population that can boast having such qualities on par with a PhD holder, let alone combine all of them. These are all very valuable things outside academia, much more valuable than what you happened to publish. Even many hirers of of professors and post-docs understand that where you published in grad school is not necessarily indicative of your potential as a scientist - for instance, rigor alone is not very important for Nature (they care about impact), but in a postdoc candidate, you might be more interested in looking at the quality of the work, not the relevance of the results.