Our experience has been overwhelmingly positive and definitely the right choice for our DC (currently in 3rd year of a social science degree and is considering a masters). We'd sum up as follows:
Pros:
Teaching, course organisation, assignment feedback and tutor support all great. DC loves their course and really rates the academic staff.
Accommodation is decent - some uni owned halls and some private halls - some have the option to return every year if you wish to. Plus a range of other student accommodation for years 2/3 if a house share is preferred.
Student welfare - supportive and helpful when needed. DC attends support groups specifically for neurodiverse students which have been great.
Clubs/societies - Portsmouth offers a good range of these and the ones that DC has joined have been well organised and friendly.
Layout - it's not a campus uni but has 'university quarter' which is studenty but is still being very much part of the city. Quite urban in feel overall but easy to get around, good transport links. Nicer parts and less nice parts, like anywhere, but there are plenty of green spaces - not to mention being by the sea!
Cons -
I can only really think of one - as a post-92 university, some people will always look down on it. It's never going to have the prestige, cachet or status of a Russell Group establishment, or a Bath/Surrey/Lancaster/Loughborough type of non-RG uni. But not everyone either wants to or can aim for those anyway and Portsmouth is a decent, solidly mid-ranking university with a gold TEF rating. Would definitely recommend!