Not sure about your local range, but cricket drops very few calls in my area (austin texas) and has clear calling most of the time. I have no complaints with the voice service.
As for the "web" service they provide...it's almost a joke. People have figured out a google url (do some looking around the cricket area here at howard) that lets you through cricket's filtering and allows access to some websites, but its sketchy and can be unreliable. Do not that this works whether you pay for their "web" access or not...so don't pay for it.
As for tethering....absolutely no success has ever been made in this department. I've posted a thread with a theory for those using a few select phones to try, but nobody has replied. I give it a 40% chance of working...but it will still be limited only to the google trick. There have been rurablings of cricket lightening up on the sites allowed to be visited on their phones, but i seriously doubt tethering through anything officially will be allowed for a long time, and unofficially depenRAB on the testing of the idea in my thread...or whatever others may come up with.
