For that price? Heck yeah it's still useful, it'll give you all the pertinent environmental data for a ballistic program like wind and density altitude. I would use lithium batteries and make sure not to store it for any length of time with the batteries in it and you should be good to go. If you use alkaline batteries and store the unit with those batteries in it you run the risk of it damaging the unit if the batteries leak since the circuit board isn't sealed off from the battery compartment.