I'll probably miss the sale, but seeing it made me remember that these were all available on here. Ordinarily, I might jump at the opportunity to snag these so easily; however I started playing these games on the console side, and after reading through some topics, it seems there are some big differences between the PC ports and the console versions. I'm wondering then, what are some of these differences that you would say are noteworthy?*

Of interest to me in particular are the basics:
Can controls be rebound in all of the games? If not all, which disallow it?
Do they play well with modern hardware (i.e. graphics/audio cards)?

I've not been burned by any of my GOG purchases, but it still seems best to try and be informed since I know some of the games on here, being older and all, sometimes don't exactly play well with modern systems even after the GOG team's work. Not to mention some of the strange issues ports can carry from the transition to a different platform.

Thanks for any responses, fairly hopeful these were decent ports!

*-As a slight note, I'm aware of the soundtrack strangeness with at least the first Soul Reaver, not sure if this extends to the other titles though. Any info on those would be appreciated. Also, any comment on the quality of the soundtracks in these versions would be great. Game music makes worlds of difference in my enjoyment of them. Thanks again!

The only noticeable difference can be found in SR1. It's the weakest port in the series. It looks better than PS1 version (increased view distance and typical PC advantages like resolution and texture filtering) but worse than the Dreamcast version that came later. The soundtrack is the most important difference but you are aware of it already. PS1 and Dreamcast used dynamic music while PC only has prerecorded tracks. The game is also locked at 30 fps, like PS1 original, but that can be modded. Controls are redefinable, but are restricted to keyboard only - there is no mouse or controller support (or should I say, there is support for controllers without analog sticks).
Technical issues. Just one but very annoying. There are sound problems on most configurations. In some cases there is constant skipping of the sound, in others the sound is fine but goes haywire after some time and requires a game restart. The only solution that I have found is using an actual Windows 98.

SR2 is a very close port to PS2. It's missing some shader effects in a few cutscenes, but besides that there are no differences graphics wise. No differences in sound department. The PC version was missing bonus material due to storage constraints but these are included separately. Mouse controls have some problems - rebinding arrow keys to WSAD makes "forward" not working in combat or free look mode. No problems stability wise besides affinity issue that can be easily fixed (see the sticky thread for details).

BO2 looks a little different than PS2 version. Not better or worse, just different. Nothing is missing though and it's still the same game. While some things may look better on PS2 (like for example mist form) PS2 is missing some details like Kain's scar. No problems with controls. Stability - the same affinity issue as SR2. It's also the most stable version of the game.

Defiance is identical to the console versions, but it's missing voice sessions in bonus section. I'm expecting that to be added separately on GOG at some point (like they did with SR2). No problems with controls, same affinity problem as SR2 and BO2.

I hope that explains everything. SR2, BO2 and Defiance were ported by Nixxes, the same company that ports 90% of Eidos games.

Thanks for the response! I'll have to try and catch these on sale again in a bundle sometime or get them piecemeal. Sounds like the only game that was kind of wonky was the first, which I fortunately have a PS1 copy of, so that's no big deal.

Ah, i was wandering why the music didn't change on context. Is there any way to mod the PC version to get this effect back or I am stuck? It's awfully jarring to play without the dynamic music after playing it on PS1 many years ago.

Unfortunately there is no way around it. It's the limitation of this version.