I consider the original Final Fantasy Tactics my favorite game ever, and I'm a bit worried about this version due to:
Okay, so I'll address your points!
The slowdown. It sounds really annoying and almost enjoyment ruining.
It's definitely the worst part of the game. The core engine, though, runs much faster, so when you are actually interacting (navigating menus, etc) it's actually better. So you win some and you lose some. I'd prefer the game didn't slowdown, but after the initial shock of OMG THAT IS SLOOOOW, I didn't much care.
Sound problem. I've heard that the sound quality is worse than the original game.
The sounds are mostly the same, but a few -- the death scream, the sound of wind howling, the dragoon jumping -- are really bad. It doesn't bother me since I keep the volume down on handhelds most of the time (lol pooping at work).
The translation. I know most people love it, but some changed such as names sound very annoying.
GOD I love the translation. I finally can make sense of the plot and the writing is pretty snappy. It has this air of being intentionally cheesy, which I dig. The changed names are almost all much worse -- Algus has a lisp now, apparently. During cutscenes, though, you will *love* the changes.
The fact that it's on a handheld. I fucking hate playing games on tiny screens, and I'm worried about that with this remake.
I love handhelds and the PSP has a great screen so I don't know what to tell you.
Also it has pre-rendered cutscenes and they are all pretty awesome. A hybrid between heavily-styled 3D animation and straight-ahead paint animating with really detailed backdrops. I wish they'd make a game that looked like this.
So yeah, this is my top handheld game right now and I love it to pieces. If you can't get past its cosmetic shortcomings, though, you're out of luck.