Having the modifier keys in the thumb cluster feels a lot less awkward than using my left-hand little finger at odd angles. And I like the fit and finish and customisation.
Overall though, I think I would have been better served by a regular qwerty, not columnar, split keyboard. Maybe my middleaged brain ain't plastic enough any more.
<small>Plus I think the benefits of columnar are oversold. If I naturally curl my fingers in and out, they kinda fan in and out, rather move in parallel straight lines. And the right hand side of a regular keyboard matches that movement pretty well. The left hand side is backwards of course.