It's hard to say, because GHz means little when estimating a processor speed. If it's a new processor, it might be worth something, if it's Intel, it might be a little better. But old Pentium 4's can be i the 2 GHz range and they'd be terrible for modern computing.
Benchmarks are a lot more accurate than guessing from GHz, Passmark benchmarks for example, but even they will vary from real world tests.
It also depends on what you do with the processor. Normal office work, internet, etc it might be fine for, but games, it might not be good for.