Marvellous is always a treat and I enjoy grabbing lunch with co-workers here about once a month. We always take out, so I can't comment on the wait service or atmosphere (beyond it being cozy and cafe-ish), but I can say the food is amazing!
The sandwiches are far from plain and the portions are generous. I love the avocado egg sandwich and the turkey club. I recommend getting sweet potato fries with whatever you order as they are fantastic.
Desserts are also a treat here, but they are very, very sweet. The chocolate lover in me delighted in the chocolate raspberry mousse-type cake I ordered here once.
Marvellous has my recommendation as a good place to grab an above-average lunch for the office or a sweet afternoon treat.