So I am part way through a vanilla play-through of PST (first time through the game), but I have been reading up on the recommended mods (particularly Widescreen, fixpack, and tweakpack).

Do you think it would be worthwhile to finish my playthrough as is (just got Annah)? Or to start a new file with all of the recommended mods? I really only plan on playing through PST once, b/c I have a large backlog of other greats to move on to, but b/c of that I want to get the best playing experience possible.

I know that the widescreen mod is incompatible with old save files, but are the other mods also incompatible? Is it an option to just install the fixpack & tweakpack and still use my old save files?

Any opinions and/or feedback would be greatly appreciated!

I did my first playthrough as pure vanilla, no mods of any kind (even the bugfix ones) and the game worked fine. As the strength of the game is its dialog, and most of the mods make only very minor changes to the dialog, you aren't really missing anything by not using them. Not really, anyway. On my other playthroughs, I used most of the recommended mods, which made it a little more polished experience but didn't really affect the core of the game. The widescreen mod in particular is a double-edged sword, as increasing the resolution makes everything smaller. So you can see more of the map at once which makes the game feel a bit less claustrophobic, but you might need a magnifying glass to see your characters if you overdo it, and the scaled-up fonts don't look nearly as good as the originals. I personally wouldn't recommend going larger than 1024x768. The fixpack makes a lot of good changes, but most of them are minor.

You're already about a quarter or a third of the way through the game, so you could restart without losing TOO much. I think you'd be missing out by only playing through it once, though, backlog be damned. It's one of the best games of all time, and it's unlikely you'll see everything the first time even if you're using a walkthrough. Still, it's perfectly able to stand on its own (relatively) bug-free and hassle-free in an unmodded state, so if you don't feel like losing your progress, you can still complete a very excellent game. So it's really a question of how serious you are about only playing it once ever, how willing you are to replay the beginning, and how much you want the extra tweaks.

I'd stay away from the mods. If it's not broken, don't fix it.

There are really no serious game stopping bugs (crashes, completely stuck) as far as I know but there are a LOT of broken quests and mechanics. Just skim fixpack readme. Anyway, you would want to start a new game using any of mods. The fixed morale system really requires a fresh install and there are probably global values that will be broken loading vanilla save into new version. I would highly recommend it, but then again I'm bias.

I played my first playthrough vanilla, and now have all the recommended mods installed. Unfortunately, something has gone wrong and I get the Art Gallery crash which makesme unable to access that area, meaning I can't do a few quests. I also believe I got a crash at another point which meant I couldn't do a specific quest, so I stopped playing. I don't want to waste heaps of time on the game if I can't even do everything, and I might run into a crash that stops me continuing the game all together.

Did you apply the patch to fix art gallery (and other small area) crashes? Almost 99% of all these crashes can be linked back to WS mod so if you really wanted to play the game with mods, you could just use fixpack. UB and tweaks but none of UI changing stuff. I don't think there are any problems with ghostdog's UI mod but there is still some instability (besides the art gallery crash that I fixed) with WS mod and PST.