Tips after a long hiatus

Well I think most importantly, the game is much much more stable than it used to be. Back in the day I remember constantly getting Bugsplats while trying to get into games and it was super frustrating. As far as I can remember I haven't experienced a single crash in the last 2 years. Also if you live on the East coast, Riot opened some servers in (Chicago I think) which hugely improves ping.

Champions balance is still busted. I mean classic Riot can't seem to ever properly balance anything right but it's significantly better than it used to be.

I highly recommend you give it a try now, I don't think it's going anywhere for a while.

P.S.: I don't think Tryndamere has ever been OP, he's just hard for new players to deal with because of his ultimate and his free crits.