I'm going to miss UMDs. If there were a sale where the downloadable version is $5 less than UMDs, I go with the download. But if they are the same price, I go with UMDs. And often UMDs are cheaper if you find them on sale. I love listening to it whirl inside the PSP. Gone are the days...
And some games like Dungeons and Dragons Tactics have no download option. If you want to play it, you have to scrounge around for the UMD on EBay.
I know there is going to be some physical media replacement and it is simply the optical drive that will be lost. Still I feel it is the end of an era. Whether they really took off or not, UMDs are pretty cool.