I have a char broil silver smoker so I can not speak on behalf of having a vertical smoker, but I love mine and I love cooking with a side fire box.
The up side is there are so many modifications you can make to a silver smoker and also they are inexpensive, usually $160 range. You can control the heat with the two intakes on the fire box and also with the stack on the opposite side.
The downside is it is heavy so you can not lug it all over the place and that is really about it in my opinion.
Again this is coming from someone with a horizontal smoker and no experience with a vertical, which oddly enough after plugging the silver smoker I have been looking into a vertical as well...something cheap for the smaller smokes on a Sunday afternoon, ya know?
Good luck and you will have plenty more opinions on this forum, trust me, and they will all be good !!!!