Villagewaspbyke i am not aware of any serious constitution lawyers who think that there is an issue with Scottish legislation in particular (whether due to unicameral legislation or not).
Well...this is awkward.
Last year, two bills passed unanimously by the Scottish Parliament were found to be ultra vires but the Supreme Court also criticised that such legislation would have required interpretation by the court to clarify what it actually meant/did (this means it doesn't meet the fundamental principles enshrined in the EU Treaties relating to legal certainty and the rule of law). These were the United Nations Convention on the Rights of the Child and the European Charter of Local Self-Government. Deputy First Minister John Swinney is on record for saying that this showed the limits of devolution. Personally, I think it shows the strength of having some limits on unfettered parliamentary power, but clearly thats not a big thing to the likes of Swinney.
You think that Professor Adam Tompkins is "not a serious constitutional lawyer"? Despite his being a former MSP and current professor of Constitutional law at Glasgow University. Try this:
"Committee Row Expert Seeks Apology From SNP" The Scotsman 13 June 2014 relating to a meeting of the Scottish Select Affairs Committee which was alleged to have curtailed evidence relating to the legalities of Scottish Independence from Professor Adam Tomkins, Professor of Public Law at Glasgow University." (best to google it).
notesfromnorthbritain.wordpress.com/2014/08/29/scotland-and-the-eu
Professor Alan Page at Dundee? www.scottishconstitutionalfutures.org/OpinionandAnalysis/ViewBlogPost/tabid/1767/articleType/ArticleView/articleId/4550/Alan-Page-Its-Not-Just-About-the-Scottish-Parliaments-Powers-.aspx
Paul Cairney at Stirling? Cairney, P (2013) How Can the Scottish Parliament Be Improved as a Legislature, Scottish Parliamentary Review, 1(1). dspace.stir.ac.uk/handle/1893/16408#.VWoy3JWJjIU
Paul Bossacoma, a Spanish Catalonian working in Scotland (do you permit him to have a view on this?) got into quite a spat with Stephen Tierney over these critical issues: www.scottishconstitutionalfutures.org/OpinionandAnalysis/ViewBlogPost/tabid/1767/articleType/ArticleView/articleId/4238/Pau-Bossacoma-Constitutionalism-and-Democracy-a-Reply-to-Stephen-Tierney.aspx
See also Stephen Tierney on Tierney, S, Constituting Scotland:
A Retreat from Politics? U.K. Const. L. Blog (8th April 2014) (available at www.ukconstitutionallaw.org/)
Professor David Edwards (in the Court of Justice of the EU) was heavily critical of the Scottish Government's minimum alcohol pricing legislation and EU law compatibility (lets just say Brexit was very convenient to the Scottish Government on that one - the correct answer in EU law is always greater taxation rather than legal coercion): Professor Sir David Edward, former British judge at the European Court of Justice from 1992-2004, has concluded in written legal advice to the group "Academics Together" that the policy "would be incompatible with EU law and could not survive challenge in the Court of Justice", available at www.timeshighereducation.co.uk/news/scottish-government-fees-stance-incompatible-with-eu-law/2015435.
Professor Onora O'Neill isn't Scottish - she is from Northern Ireland and an internationally renowned human rights expert, but she has expressed her concerns over human rights in Scotland in O'Neill, A, Human Rights and People and Society, in Law Making and the Scottish Parliament: The Early Years, Sutherland, E, Goodall, K, Little, G and Davidson, F (eds.), Edinburgh University Press, 2011, where she writes "It is a cause of some disappointment that Scotland's democratic legislature should be so passive on the issue of human rights protection in Scotland and on holding the Scottish Government to account on human rights grounds".
The only two I can think of who are not fairly critical of Scottish legislation are the two who spell their names in the Gaelicised manner. I wonder where their political compass lies? None of the others agree with them.
Bear in mind also that many Scottish universities now do something that is considered taboo in any other democracy and which is not prevented by law: they require academic writers to have their submissions for publication approved by their institutions before they send them off.
Theres also a big problem with several pieces of Scottish legislation that I haven't mentioned yet in EU terms - the principle of proportionality. Many Scottish pieces of legislation would fail simply because the penalties for transgression are simply too high and in many cases, higher than equivalent criminal penalties. Theres also often a bit of a problem in terms of Article 41 of the Charter.
There aren't that many constitutional writers who write about Scotland (its not an EU member state so why would there be), but I think thats a fairly good indication of what the prevalent thinking is. Deep, growing concern.