On feature of (Nordic party list) PR that irks me: With near perfect proportionality, you loose (geographic) ties to a specific block of voters. Because a large proportion of MPs are elected on the coat tails of "vote magnets" and the general performance of the party, the party becomes more important than the candidate. Owing your mandate to an artefact of the D'Hondt method and not the fact that you got more votes than the other guy does no favours to your attachment to voters.

I'm fairly new to the UK, but it seems beneficial to me that MPs have exactly one well defined constituency and all voters have exactly one MP (even if it's one they didn't vote for) that represents them in parliament.