First thing's first - the texture. Sheet masks are weird. And drippy. And squishy. And messy. If you're a bit squeamish about slimy weird things - you'll not love 'em. Just a heads up.
If you can get over the squishy, paper-gel texture enough to get the thing on your face, they double up as a great way to terrify your spouse/dog/postman/mum, especially as you'll be so soothed and chilled out by the whole experience that you'll definitely serenely answer the door looking like a ghost that's just done the Great North Run.
Most of the masks, regardless of brand, have one or two specific aims - you can see these at the top of the Tony Moly packaging, and on the back of the skinfood masks. Thankfully, most of them have a very light citrus/floral/otherwise inoffensive scent - no broccoli face here. You pretty much just stick them on your face and don't move too much for about 20 minutes. Bliss. This staying-still notion in itself is a good enough reason for me to pick these up!
Honestly? I find the main benefit I get from most of these masks is hydration. Lots of it. I use the leftover extra goo in the packet to moisturise my hands too - it's got a serum like texture across the board, and leaves no residue once absorbed. Hydrated skin is happy skin, and I find that these really do the job without overloading my oily complexion at all - this is an accolade, as I have pretty oily, dehydrated skin.
As for spot-clearing/pore refining claims, it's hard to say, but I do find my skin is much brighter and generally better hydrated after a Vogue-reading session with one of these bad boys on. For the price, they're not only a lovely experience, but go a long way towards boosting hydration, even with an oily, temperamental complexion.
Have you tried out sheet masks? What did you think?
Some links above are affiliate links. All products mentioned bought with my own money.