Heaven is perfectly fine if you take it on it's own, for entertainment purposes, perhaps comparing to other Heaven scores, and not trying to use it as a metric to gauge anything else. Stand alone benchmarks such as Heaven can only tell you how the equipment performs with that benchmark. If you want to know how Doom is going to perform on your setup, you need to benchmark Doom, not Heaven. If you want to know how Minecraft will perform on your setup, Heaven won't be applicable here either.
Also, like most games, Heaven has different settings you can run it using. If you want Heaven to run faster, turn down some of the details.