If you don't know, or have no experience, anything you can do with a computer, just like with a car, or an airplane. could be dangerous.
Is it worth it? thats the big question here, and one that you didn't do.
So in order to answer that question (is it worth it?) you have to ask yourself a few other question and share the answer with us:
What type of computer do I have?, Motherboard, CPU, RAM, PSU, GPU, Storage?
Am I upgrading my celeron/core i3 to one of those core i5 cpus?
If thats the case (upgrading), whats the main and secondary use of the PC?
If the main use of the PC is gaming, what kinda of games do you play?
Do you have a limited budget?
Are this cpu parts you have lying around, and just what to put on good use?
Do you have the right cooler and thermal paste, if you were to OC a Core i5 2500K?