Medium budget, Shrooms has a pleasant degree of gloss and decent acting.
However, let's face it, the entire plot is just a set-up to get teens in the woods and put them in harm's (and stupidity's) way. A small party of American students fly to Ireland to meet up with 'Jake' (a charming Jack Huston) who used to attend college with them. The educated tearaway with a gift for drugs, Jake is promising to show them the 'trip' of a lifetime by introducing them to magic mushrooms while they camp out in nature so that they can enjoy the experience undisturbed.
The group's relationships are nicely fleshed out with just a few scenes, with best buddies Lisa and Tara clearly viewing the less slick and well groomed Holly as an outsider. Holly is dating the skater kid who thinks he's a martial arts wizard, Lisa is dating dumb testosterone on-legs Bluto, and Tara is sweet on Jake.
The film has a nicely 'bleached out' visual look that makes the Irish woods feel eerie, and after the almost obligatory encounter with excessively retarded natives, the kids settle down at camp. After some medical drama and some nicely eerie scene-setting by means of an excellently told campfire story, the main plot kicks in, and the mushrooms start to affect people. It's a movie where you have to indulge it and go with the flow. Are they all tripping, or are they really being hunted by someone?
There's a lot of panic and running around, some enjoyably staged violence, and an interesting resolution.
It's not the best or the goriest horror you'll ever see, but it is memorable and enjoyable.