I need a word that means 'better than expected, but still not good'. It seems that every 'better than expected' word has a positive connotation, what I want is a neutral to negative connotation. It seems that language always has words for the most ridiculous stuff, then when I need something it doesn't exist xD So is there a word for that? Or am I out of luck on this one?
A single adjective for this doesn't come to mind. I think the most natural way to express this idea is to say, "It's not as bad as I expected (it to be)."
That conveys the notion of something being better than you expect it to be without suggesting that it's actually good.
Another option would be the phrase "merely adequate."
When you use comparatives like good, better or best, by default, you project a positive connotation.
As you can imagine, the opposite set of comparatives would be bad, worse or worst respectively.
So you can't say something is better with a negative to neutral connotation.
Coming to your question
what I want is a neutral to negative connotation...
You can perhaps say this using an idiom (for a neutral connotation)
It's good, but there's still plenty of room for improvement
Better than last time, yet I see a lot of scope for enhancement
P.S: Or if you're British, you can just say that it's quite good! ;)
The word modicum is pretty close to being a one-word synonym for "better than expected, but still not good," as in
We achieved a modicum of success.
In this sentence, modicum connotes there was some achievement of success, but only a modest amount. In other words, there was a great deal of unrealized potential in the amount of success achieved. You'll still need some accompanying words, of course, but modicum is pretty darn close to being what you're requesting.