Classes are exactly like on retail 4.6. Gunners, bards and SMs are still mad OP in PvP. You better run if you see any of them. Sins are viable if you have stable 40 or less ping and skill to play that class. Gladis, templars and dps chanters absolutely require extendables for PvP, but those are extremely hard to get on this server. Many have them already from previous events, so you will struggle to get them.
Ping is stable. My ping here is perfectly stable, staying around 44-47 (Living in Ireland). Never had issues with it.
All end game instances are fully functional without any issues or bugs (Unless you count Sauro 1K bug on last boss that existed on retail).