I like analog devices as they are usually solid. Digital devices can be great IF manufacturers don't cut corners, which they all do now a days, resulting in a product with high variances in parts that add up.
Looks like you got a good deal on that hydrometer!
Edit, a wet bulb vs non wet bulb is basically a temp measurement on a regular thermometer and a thermometer that is literally wet inside of a sock or shoe lace. Take the difference in temp and there are charts to figure out what the relative humidity is based on temperature differences at particular dry bulb temps. At least this is what I remember.