The tolls are high if you don't have an EZ Pass so if you plan to spend any amount of time in the Houston area you absolutely want to get the pass. If you are just passing through you can pay or you can detour to non-toll roads. It's not hard to do but it does add miles to your travels.
Houston is our home base so when we are not traveling we often head to Houston. We have the pass and even when we don't use it for years it costs us nothing. When we return it's still active and we are good to go. We keep one on the toad only and if we pass through with the MH and the toad we get charged the 5 axle price. If we are just in the car we get charged for just the car.
It has worked out very well for us.