Again, like the others above, I am not a Liverpudlian or Scouser but have spent a fair bit of time there as my fiance is a native.
The city is not as big in terms of population as London or Birmingham, but is still in the 600,000 people range so has a large city centre with enough to satisfy your needs - whichever they may be (including a huge shopping centre). The city does have negative reputation but judging by my impressions from the late 00s it has been revamped (if that reputation was deserved to begin with) and has plenty of nice areas. Check out the Docks, a really beautiful part of the UK, let alone Liverpool, and the huge Anglican cathedral (5th biggest in the world).
As people have said it has a vibrant cultural scene with plenty of bars and venues to cater to all tastes. I have uniformly enjoyed my time there and while there are bits to avoid (Toxteth for example) that is no different to any large city anywhere.