Reading down through the reviews I see a lot of people that are happy with the product and or service given to them by Irwin Cycles; I also see an odd few that were not happy at all, what I find interesting when reading the unhappy reviews it appears they are unhappy because things did not go perfect for them.
I've been riding for many years and been around a lot of shops throughout the southwest and I haven't found any shop that is perfect. What I have found is the great shops always try their best, but trying your best is an interesting thing because a person's best is different each day; since shops are run by people the shops best will be different each day. So if they consistently are giving me their best and I happen to come in and find their having a bad day (we all have them) I know they are still trying their best to tend to my needs or someone I sent to them.
The Irwin's run a great shop and they are going to take care of your bike like it's their own or a close friend. My friends that live on the West side of Vegas this is where I send them for bike service/repair; they're also pretty good wheel builders.
So go in there with confidence, because you are most likely going to go home as a happy customer.