I always have the same experience at Mellow Mushroom in Rocky River. Great pizza and beer with mediocre (at best) service. So the service is a 2-star experience but the pizza is a 4-star.
The greeting/seating is always weird -- the front never has anyone but eventually someone will appear and seem unclear why you are there. Then it's always a wait for someone to take your order after you are seated and if you want anything later plan to get up to find someone. No one is rude but barely helpful is the best description. I've dined at Mellow Mushroom located in other cities and the service has been good. But because they delicious gourmet pizzas and a nice draft beer selection I'll dine there occasionally. I'd say give it a try and see what you think.