The term run-of-the-mill was coined for this type of film. A film with no real inventiveness, one that has very little to add to the genre, but which expounds on all the familiar clichés.
It tries, but there in lies the problem. It tries to be too many different things- horror, teen road movie, drama, comedy and the end result is mixed at best. That's not to say it isn't well made or very badly acted, it's neither, but it's just so tediously average and not successful enough with its scare-tactics, or lack there of.
Only if the following things scare you will this film do its job as a horror flick...
Teddy bear key rings
Boxes falling over by themselves
Bad dye jobs
Tree branches swaying in the wind
For a film that's billed primarily as a horror movie it's surprisingly gentle. Granted, the score has all the necessary violin shrieks in all the right places, there's gore (in moderation), there's the array of stock characters (the naïve one, the funny one, the promiscuous one, the creepy one), but there really isn't a great deal of tension cranked up throughout the course of the film and the pay-off is banal to say the least.
'Solstice' also suffers from an incoherent horror premise, one that's based on one of the biggest clichés in movie history- the dead twin. There's only ever going to be one outcome where a twin is concerned, so in waiting for that to happen I found myself irritated rather than intrigued.