The FX in this film are quite good and the film is full of gruesome goodness. The concept, is quite interesting and while I think it needed a bit more fleshing out and backstory... I'm happy if someone tackles that in a sequel.
The film isn't all that unexpected once you get what's going on and short of the concept, isn't all that original... but what it does do, it does well.
I would easily recommend this film to those who I think would dig it. The nature of the film and the gorry aspects of it might turn the lesser minded viewers away ;)
1) Are characters interesting?
2) Do things make sense, or do characters do stupid things for the sake of the plot?
3) Is the creature itself interesting?
If all three of these of these questions are answered in the "no", there's generally very little that can help the film. If all three of the questions are answered in the "yes", it's generally going to interest me, possibly even keep me riveted.
Splinter is not a perfect film, but I liked most of the characters, none of them really seemed outright stupid to me (except the one female cop, though I see why she acted the way she did to an extent), and the creature itself was bizarre and edged more towards believable than unbelievable (if one doesn't look too closely, which one really can't for this kind of film)
Regardless, if you aren't much a fan of this sort of genre, you can safely give this film a pass. There's nothing truly groundbreaking or innovative about it. But it still is nicely tied up, doesn't make your brain rebel from the silliness of it all, and makes for an overall effective horror film.