I may have a contrarian view but I believe that the current deal is a great win for the British Government and a big political loss for the European Union.
Thanks to the Northern Ireland issue, Brexit in the current form designed by the tentative Withdrawal Agreement delivers for the U.K. both the end of freedom of movement and also keeps the U.K. in the single market.
Surprisingly, this is a huge win for the Leavers and the British Government (at a high price, certainly, but they have nevertheless been able to fracture the unity of the 4 freedoms) and I am surprised people in Britain are not appreciative of the fact that this is already an extraordinary achievement by the negotiations given the mandate received by Theresa May after the referendum (ie. end at any cost the Freedom of Movement, one of the EU biggest achievements, which nevertheless the British Public has been groomed for decades to detest).
Why would this be bad for Europe?
My take: if this deal has been granted to the U.K., why not granting it also to Poland or Hungary or Austria? Ultimately, they are governed by the same breed of opportunistic and xenophobic ultra right politicians.
Before granting the U.K. access to single market and custom union, the European Union should have asked much much more to the U.K. (specifically in financial and political terms) so that other countries would be much more scared to pursue the same path.
Much remains to be seen (if the Withdrawal Agreement will be approved by the U.K. Parliament or not), but the British Leavers should appreciate that this is already a hell of a good deal for them.