However, it’s vastly better than FPTP when there are more than two parties.
In the US, they’ve managed to prevent additional parties from emerging, probably because of their system of primary elections, and if the opponents of AV were actively proposing to introduce a similar system here, I’d be less reluctant to listen to them.
The problem with FPTP is that there are a lot of constituencies where the votes are fairly evenly spread, i.e., situations like SNP 26%, Labour 24%, LibDems 22%, Tories 20%, and it’s really problematic to have a winner who only got a quarter of the votes (which, if turn-out is bad, might mean that less than 15% of the constituents voted for the winning party).
I’d much rather have proper proportional representation – I’d prefer something like the Danish system, but the system used for electing the Scottish Parliament or STV would be OK, too.
However, this is probably the only chance we’ll get for decades to change the electoral system, and AV is definitely preferable to FPTP, so please vote Yes!