While last year's Celcius J GTX was good at keeping water out, it wasn't so good at insulating your feet from the cold. To address this issue, Northwave has made the previously slim Celcius into a more meaty-looking affair. It's still a more attractive boot than the Shimano, if not quite as feline as the Sidi.
Where the Celcius scores is the fit - it's by far the most luxurious in the test, really cosseting your feet. The fit is helped by the fact that Northwave uses a lace and Velcro combo to secure them to your hooves. The lace does up using a slide lock, so no worries about tying laces with frozen fingers.
The outsole provides decent grip and, like all the shoes here, provides the option of adding twin toe studs if you think you'll be hiking up slippery hills.
One small detail that niggled was the mesh finish to the front section; although it was waterproof, it became clogged with mud very easily after winter rides and was pretty fiddly to get clean.
Water can also get into the top of the Celcius because the top cuff isn't waterproof, and this is an area where the superior Shimano MW-02 retains a definite advantage over this shoe.