If you look at her professional profile on the Chambers where she is employed (which shows the same photo), she appears to have achieved a great deal in a relatively short time, including an MPhil in Criminology at Cambridge. She has published articles in several newspapers, including The I, New Statesman and Guardian, was "instrumental in the criminalisation of forced marriage and was voted Human Rights Barrister of the Year 2013.
I agree that she did look pretty serious on Newsnight and did not portray the "fluffy" sort of image of women that we frequently get on TV.
As this incident has attracted more and more coverage her photograph has been described as "flirty", "smug", "provocative", "glamorous" - but now there is a complete about turn and this has changed to being "po faced" and lacking in humour. She didn't come across as a particularly warm or sociable person but we don't know her and what's that got to do with it anyway?