The lag sound loop is horrible as others have mentioned repeatedly. I, like many, created new toons when I5 went live. While the sound loop started from the get go, I did not start experiencing the lag dramatically til I got my travel power at 14. I noticed that when traveling from mission to mission with my travel power (for all of my toons not just the new one) the lag was horrible, but generally ceased when I enterred a mission. Even when I used my Super Speed etc in a mission I still did not experience the lag I had when in the zones traveling.
I think the changes to damage resistance based toons a good change for the most part. I still think the percents are too low for non-S/L damage for Inv/ or /Inv.
I think the +Def changes are exceptionally bad though. I made the mistake of rolling up a Stone Tank for I5 not remembering that Stone Armor is a +Def ability. Doh! I have no problems against even con minions, con+1 things get interesting, con+2 means a probable death in a non Sonic or Empath member team, and con+3 or above means certain death regardless. This is not just a low level problem due to the disparity/lack of the powers available, enhancement quality available, etc of myself and the players teamed with as I have had the same problem with my /SR at level 40. Thank goodness my /SR has Elude. The only time the issue has not been in effect has been duoing or solo at Heroic or Tenacious level missions.
The change to foe spawning does not seem to work as of yet. Almost every building mission has had numerous spawns in close proximity to one another and has made avoiding big melees near impossible. With my Tank's +Def she has just not been able to handle the number of attacks directed her way. Even with the Taunt change. It says something when, as a Tank, I'm hoping that a few of the baddies will not agro on me and instead divert to the scrapper and blaster just so that I have enough time to pop an inspiration or hit my self heal. The other evening I actually avoided using Taunt after the initial pull because it put me in the red so fast I was dead and just did not know it yet...lol. I did not hit Taunt again til I was at half a bar of health after gobbling 3 Respites and noticing that the /Inv scrapper was in the orange. I hit taunt and saved the scrapper but died. The scrapper still died if I remember correctly.
One possible fix would be to shorten the recharge of self healing powers if an increase in +Def is not wished by you. This actually may be a "possible" solution to all of the +Def sets in the future with Quickness (one of those who love the power as is) for /SR getting an increased Health regen that would be enhanceable with more Health slots added to the power since they do not have a self heal.
Sometimes I really miss those days. Oh well, all for the sake of balance I suppose. What I really regret is not at least taking a screenshot of the times I novaed a whole map or most of an island of Rikti Monkeys (curse you old-school Zookeeper!!!!).