We have had the Overdrive for about 4 months now and have already had to spend $27 to ship the first defective unit back to Sierra for repair. We just got the second unit back and a week later had the exact same battery issue that we had with the first one. We had to purchase a new battery for $13. We have had no luck at all complaining to Sprint as they just say to call Sierra as it's their product. Sprint is the one that sold this unit to us and they are putting their name on it and yet they will not take care of the problems that many customers are having. The battery overheating and bubbling is a common known issue and so far as I can tell they have no plans to address this issue or make it right with existing customers. When our 2 year contract is up we will definitely be shopping around with Sprint's competitors. Buyer beware that this unit is a very poor design and Sprint will not support any hardware issues that you have with it.
I only gave it 2 stars as it does sometimes work when you have a fresh battery installed that hasn't yet bubbled due to overheating.