I never use DVDs for playback. Basically ever. As soon as I buy a new DVD, the first thing I do is rip it and import it into my MC library.
However, I recently received one of those DVD board games (Scene It), so I actually have to use the DVD to play the game. I discovered a couple of issues using MC (and other software) for playing this game. The DVD worked in MC, but when I tried to use my remote to navigate the DVD menus, I got the MC OSD instead of the DVD Menu. Right now, the only filters I have installed that are relevant to this are CCCP and Nero 6's filters (I believe MC was using Nero for DVD decoding, but I'd have to check to be absolutely sure). I also had an issue that using the Track Forward button didn't properly skip through a question we may have already used and there was no easy way to activate the DVD "Return" button feature (which was used in the game to "go back"). I tried ESC and it didn't work.
This was obviously no good.
When trying to use MPC for playback, I had some of the same issues (the track forward and Return problems) and it also sometimes reported that it didn't support the scripting features the game needed (oddly, one of the 4 times I played the DVD in MPC it worked without this error, but the rest it gave me the error).
I strongly suspect that this is because of my lackluster DVD decoding filters. However, since I very rarely use actual DVDs, I'm hesitant to buy TheaterTek or other similar DVD playback packages. I'd prefer to just use MC. I am willing to buy a decoding package for a reasonable price though. My HTPC has ATI/AMD hardware (though it is an X800XT so it doesn't include any H264 acceleration hardware so I don't need to worry about that).
What experiences have people had with different decoders? What is recommended? I'm, of course, considering the Nvidia PureVideo decoders and the Cyberlink/ATI Decoders (which I actually already own an old version of because I have a AIW X800XT card). Are there others though? Anything free work well (dscaler and FFDSHOW)?