Good entry level curb, I think. It's not freaky huge and the roller would definitely help the horse relax some. The port is a gently curving, not harsh square. The shanks have a good bend so the horse is 'alerted' of what your doing quicker then a straight-shanked mouth would be doing (much harsher). It's similar to the one I ride Red in, except his doesn't have a roller :)
Good bit if your horse neck reins and responds to legs. If you need something for direct contact, a three piece snaffle is the way to go, then graduate into something like this. Red, for example, moves off of leg and neck. Rarely do I have to ask more with the inside rein. If he needed a lot of direct reining, then he would be in a snaffle yet.
I would rather go with a sweet iron or copper mouthpiece (tasty), versus a stainless steel one (bland).
Wait! I'll fix it....