I went for my first time last night. I was won over by the food, but put off by the service and atmosphere.
Our server greeted us promptly, was very friendly and was quick to take drink orders. After that, it kinda went down hill. We waited a while for him to come back to take out food order. (Sidenote, we ordered The Don and damn it was good!) The server came by once after our pizza was dropped off at the table and then we didn't see him again until he brought the check. I sat with an empty water for a good 10 minutes. It didn't seem like they were short staffed, so not sure what the deal was.
Another note....don't get the table for two in the row by the kitchen and next to the bathrooms. You get the be distracted by the servers drumming at the server station while they wait for orders to come up. You have people standing right behind you if there is a line for the bathroom. You get to hear the servers screaming and carrying on. You may even get dusted with ground pepper while a server swings the grinder around.
I'll be dining at Grimaldi's again. But if I go back to that location I definitely won't take that table.