phoenix implement splicing very well, I'm really impressed using it. They made a fantastic non-custodial UX with the right tradeoffs IMO (in particular with bolt12 adoption).
The only problem I have with it is the single point of failure in acinq. Having something like phoenix but interoperable openly with multiple nodes would be a peak in lightning network wallets. Electrum is trying to do something like that, but it still need a lot of work.