Jailbreaking my iphone4 from verizon.... Is this okay?

can i jail break my iphone 4 from verizon and still be able to use as a phone? i'm almost due for an upgrade and was thinking about getting an iphone 4-or-5 not sure but i'm pretty sure i'm going to get an iphone. Is my phone going to be okay and still useable if i jail break it? I just hope i don't get into any trouble if this is done. And i hope that it won't mees up anything else in the phone. Please i phone users please give me some info about the i phone... Thhank you!!!