At the time of writing RR is the world's tallest and fastest stand-up coaster. I am not a big fan of stand-ups as I find them a little uncomfortable and the extended loaded times can be frustrating when the lines are long. The ride is very impressive to look at and features six inversions. The station is well themed particularly outside and the station music is pretty cool.
The first drop is huge for a stand-up and provides a great thrill in the front seat, however, if you're in the back seat you may find yourself being whipped round a little bit as the train comes off the lift hill. The whole ride is incredibly smooth in the front, but slightly more jerky in the back, but still enjoyable.
All of the inversions are good, but the final corkscrew seemed to have that extra little bit of speed, which made it more exciting for me. If you are sitting in the front, you may also be lucky and get a tiny bit of airtime on the crest of the hill after the first corkscrew. Unfortunately, parts of the layout are a little uninspiring; it just goes from one inversion to the other with a flat piece of track just above the ground in between the inversions. The Riddler is still a wonderful ride, but for me it just doesn't have that special something to make me want to go straight back on it and never get off.