Okay, I'm trying to make sense of my thoughts on this, but feel I ought to as I'd been a defender of the scheme (though in my defence had always caveated with 'if it's done properly'). My main gripes (that will be communicated to the Council) are perhaps more stinging to me because this could, should be a wonderful piece of infrastructure...
Disconnected
This was the biggie. It was only ever going to work if it was properly connected. The problem, though, isn't just that it isn't properly connected, but they seem to have gone out of the way to make it as awkward as possible. Heading off the lane at either end you get directed up onto the pedestrian crossing, putting you neatly in the middle of two sets of motorised traffic lights, with nowhere to go other than cross the road to the squares and from there to.... Hmmmm. Joining the lane from Charlotte Sq isn't bad, given there are specific lights and a turning lane (though you've got to cross two lanes of traffic to get there and it takes a confident cyclists to take the lane from Princes St as is the best way to approach it). Coming from anywhere east to the lane is just mind-bogglingly awkward, traffic-busy, and tramline laden. So you have this little oasis ostensibly to get unconfident people riding, but no way for them to get there without awkward and busy roads.
The Switchover
I can only surmise this is because of the need to have a different traffic order to switch the traffic flow direction for the motorised traffic. Whatever, it's nonsense. The middle switch is kind of okay. The swing around the statue at Castle Street heading west is bonkers given sightlines and traffic expectations. I suppose this is a trial, and so they'll be seeing if the (well-implemented) same side, traffic-light controlled bit to the east is better (it is, let's tell them so).
The potholes
All of that work gone into lines and shifting sets of lights and so on, and what do they leave? Ruddy big potholes in sections.
The unfinished nature
It's open now. It's in use. I remember complaining about certain aspects on Twitter and a Councillor telling me to wait till it's open. Well it is. And still the push button for the cycle crossing on the east end doesn't work; there's no thought for where to put cyclists at either end to leave the lane; and there are still no bollards to stop motorised traffic travelling down it despite repeated promises.
Lack of Protection
Ties in with the bollards. There's nothing stopping anyone driving onto it, or (as the picture above illustrates) completely blocking it to carry out works, with no alternative provided.
Sight Screens
I don't mind the outdoor eating areas, I like them in fact, bringing that European flavour to what should be a European style street (i.e. pedestrianised...). But what is with the sight screens just before each pedestrian crossing? They're a nice idea, just not where they are!
Just... Slapdash...
I get that it's a trial, but for a trial to be fair, for a trial to show if something like this would work and improve the area, it needs to be 'worthy' of using. If I'm on it I'll use the lane for the first two sections, then ignore the switchover and carry on along the road because I'm a confident enough cyclist to do so; those lacking confidence can't get there because it's marooned in the middle of the city. Ergo, stats will show it being under-utilised, and not required. 'We gave cyclists a completely segregated area, they didn't use it, too bad'. It's a fairly typical half-hearted attempt from the city attempting to get, what was it, 10% of journeys by bike by 2020?
Depressing to be proved wrong, but wrong I am. Like I say, this could and should be perfect, but once again rather than studying those who have already done this before us and simply copying the template, Edinburgh Council has gone with its own plan, and... Well, we'll see what the results of the trial are.