This restaurant has been a staple for sushi lovers, including myself, for a long time. I've been coming here for AYCE only so I can't speak much for the regular menu. But I can say their AYCE has always been solid and consistent which is why it seems to be always busy and which is why your service may take a hit. Be prepared to wait to be seated in the small restaurant during peak hours and to occasionally wait for your server or sushi chef during your meal because they are tied up.
They have extended hours for the late night cravings. For the novice sushi eaters, there are plenty of pictures on the menu to aid you. If you're sitting at the bar, the chefs are more than willing to answer any questions or fill any requests. Keep your eye on the chalkboard for any specials also.
This last visit I sat at the sushi bar just after opening on a Saturday and had a solid meal of appetizers and nigiri. The chef was busy but made sure my meal was flowing smoothly. I didn't get any rolls as all of the 30 pieces of nigiri were delicious and enough to satisfy me. They had two clam specials: Asari rayu and orange clam (I took pictures of both but they were pretty crappy so I didn't post them) which both had oil and sauce respectively that elevated the clam which is something I normally don't order.
Sushi Mon is not head and shoulders above the rest and they're location is not convenient for me. I am still a fan though and will continue to frequent there but it will most likely be only late night, or if I happen to be driving in the area and the wait looks reasonable.