I'm not a full time cav and this is probably my 5th gen out of ... a lot ... that I've spent on cavalry. I've had very little problem adjusting to the new Heavy Lance speed... but only after I put a decent amount of WPF into polearm. Prior to that, I simply used other polearms... the light lance and even the red tassel spear (when you fall off horse you can use it as your secondary) were usually my choices.
It is simply a matter of timing and getting used to it. This isn't much different than when you were on horseback and had 1 WPF in Polearms and tried to lance someone with the Heavy Lance before the batch. The only difference now is that you will had to deal with that slow speed even after a relatively decent investment of WPF into Polearms. At approx 150 WPF though, it feels relatively quick again.
The Heavy Lance is still very viable, but you have to get used to the pros and cons of it now. For example, if you intend to run through a crowd at lightning speed on a Courser and lance 2 or 3 infantry, you won't be able to pull it off anymore because of the time it takes for the lance to reset/recover. A light lance may be capable of this, but the moment you run into a cavalry charging you with a heavy lance, you will have to decide if you want to take your chances on him outreaching you.
Before playing a cav again I thought the change was unnecessary and a waste of time. After retiring, going cav, and getting into the lvl 20+ range... I think it adds some variety that was sorely needed. I actually plan to go 1h cav next time because my previous build was a 2h with riding (so I could heirloom a horse) and I had a blast with 1h on cav when I was just messing around... and it was rather effective.
*Note - the sidearm options though really do suck... but I actually like it this way. I have an heirloomed shortened spear that I carry and if you are a dedicated cav on foot... it's hard to be effective with it. The reach is awful without having athletics to move around and anything more than a shortened spear and you will likely start bleeding more money than you find it worthwhile because
you shouldn't be on foot anyway. Remember that last part... you are effective on horseback, so try not to fall and there's no problem