I don't recall why, but neither plugin will download art, despite it being available via the API and there being a "Download images" option in their configurations. And they're plugins, not scripts, so this is not something you can modify.
Other than downloading a backdrop of the cast for a series (for reference), I haven't been very interested—because MC hasn't had the ability to display them. But for series, now it does. And it downloads and displays the backdrops automatically, so there's no need to use PVD to collect them. Hopefully, they'll do the same for movies soon.
Neither PVD or MC will get episode images. I've been relying on automatic screen shots for that. I set it for 12 or 16 shots, then manually set one as the poster and delete the rest. It only takes half a minute, but it's tedious.
Despite the fact my process for handling episodes is largely automated, I'm finding the bits that aren't somewhat tedious. I have to rename the files my torrent client downloads, run the file scanner to get them into PVD, and then find them in PVD to pick a screen shot for a poster. So I'm testing
NEW: MC16 and Sick Beard Integration. It's not the easiest thing to understand, but so far (only two days) it seems to be an effective solution. It finds and downloads torrents, which my torrent client sees and automatically downloads the files. Sick Beard, which has already downloaded all the meta data and images, renames and moves the files when the downloads are complete.