I think you should give HL2 a chance. It can be enjoyed even without the first game. You have already played the first game a bit, so you know the deal (experiment gone wrong, aliens everywhere). HL2 takes place 20 years after the incident.

There’s fewer annoying platforming sections for instance. The puzzles also involves proper Havok physics, which is easier to manage.

The story is also a step up, with proper named characters. The baddies are also better developed and has a better reason to be the baddies.