Side note: Works doesn't completely check grammar, and Office Word's grammar checker notoriously sucks. The latter points out errors where there actually aren't errors and skips over the stuff that should be marked.
Meanwhile, spell checker only covers spelling errors, so it'll only probably fix the typo problem. And even then, it doesn't catch things like Pokemon names unless you actually enter them into the dictionary.
So, yes, it's recommended to get a beta reader.
Sorry for promoting derailment, by the way.