Can't say I feel guilty about liking these but if we're talking about mediocre games I love that would be:

• Drakengard 3 - simple, repetitive gameplay, huge amount of asset reuse and terrible performance if you're crazy enough to play it on PS3. It also has a really engaging and tragic story, full of weirdness unique to the series (well, the first game anyway, haven't played D2 yet).
• Kane & Lynch (both games) - they're rough, gritty and don't pull any punches. Pretty divisive in terms of gameplay though I personally think it's thematically consistent and adds a lot to the atmosphere. My favourite games from IOI despite not being as well designed or polished as the Hitman series.
• Oni - 2001 action game by Bungie. Really cool hand-to-hand combat system, huge empty levels, simple story with wannabe Ghost in the Shell elements.
• Starbound - lots of hype about Terraria in space, lots of wasted potential and cool features that didn't make to the final release. I tend to prefer beta versions (mainly "Glad Giraffe" beta) but the final one also seemed alright based on what little I played of it. Definitely not as good as it had chance to be during development.
• Scarface: The World is Yours - budget GTA clone based on the 1983 movie with Al Pacino (it's actually a sequel). It looks bad even for the time but it plays well enough and has some neat mechanics which made it stand out, if only a little.
• Tresspasser - the infamous Jurassic Park game with full control of your arm and focus on physical interactions with the environment. It's a bit clunky and far from polished but it's an interesting experience nonetheless.

That's all that comes to mind for now, I might update the post if I remember anything else.