Only flown with them a few times and always between London/Singapore, but my experience has been excellent with SQ. All Y class flights on A380s/B777s. Particulars:
Ground handling - polite, efficient, helpful. No problems to report, but I've not had dealings with contracted handling agents at airports other than Changi.
In-flight accommodation - Good seats, particularly on the refurbished B777 and good amenities. I found it well worth paying to select an emergency exit row seat before check-in for the extra leg room - I'm over 6ft tall.
In-flight catering - Decent meal selection including drinks. As many snacks and drinks (alcoholic or otherwise) as you desire throughout the flight.
In-flight entertainment - Larger IFE screens than I've had when travelling F class with Swiss and Thai. Selection of films/tv programmes that I've not seen equalled in Y class.
Overall I'd be prepared to pay a premium to flight SQ, so if you can get them cheaper then go for it. They do offer promotions from time to time though, so perhaps that's why they're cheaper at present. Hopefully others with experience of the route you're travelling will be able to offer something specific on that.