I absolutely love mine. Personally, I don't think there is a better base layer. I've been wearing it for a few seasons now. I probably need to pick up a new one this year. You can only re-sew a crotch so many times.
I've been riding strictly with a Ninja Suit for four seasons. Wouldn't consider getting anything else. I had the synthetic suit for the first 3 years, and upgraded to the merino last year. The merino actually isn't that much warmer than the regular synthetic, but the fabric is much nicer against the skin and merino wool combats stink and bacteria much better - great for multi day trip or a weekend in the backcountry where you can't wash your base layer. They do have an expedition weight Ninja Suit for colder days though.
Get the Merino if you can afford it - I have a Stoic 200 Merino hoodless ninja suit, and it was the best baselayer purchase I have ever made. Wicks moisture better than any of my synthetic baselayers, doesn't get stinky as quick, and temp is fairly well regulated IMO