Yes, Horary Astrology is completely valid and it totally works, especially with the planetary hours determining validity. I've found several objects using it and had answers to questions verified.
Do not use Whole Sign Houses, Placidus/Regiomontanus work best with it.
Also bear in mind, some Horary Astrologers discount the influence of Neptune, Uranus and Pluto which is a massive mistake. Ema Kurent is one of the best here, I can recommend her books.
Also it is best not to ask abstract questions with it at the start. Don't ask things like "who is my GD", you will likely misinterpret the result. Stick to things like "where are my keys?" at the beginning.