I have used Monaghans three times since aquiring a Mk1 Octavia VRS in August - twice for two bulk parts purchases, and a third time for them to fix a broken window regulator. They are less than 1 mile from my workplace so very convenient.
I found the lady at the parts counter very friendly and she gave me a discount on the second visit. As a first time Skoda owner I was surprised at the low parts prices.
The window reg was done for €180 inc. VAT & labour which was a tiny bit spicy but the convenience swung it in their favour.
Overall I would class the place as friendly. I have owned a wide variety of cars and have used most of the dealers around the town, mainly for parts and often with horrendous results. I will continue to deal with Monaghans, and would recommend them.