I had these So1es on my GT hardtail for a year, they are OK for dry days and shortish rides. The problem is they are single piston brakes so only one piston comes in when you brake, the other is passive. This means that on wet grindy long rides, the brakes start to fail, and you need to get off the bike and allan key the pistons in a bit. In a wet 4 hour "challenge" ride in Grizedale last year, I had to do this twice. When they are set up right, they are not as shite as other people say but you need to bear this in mind. Given that shopping around on the likes of CRC and Merlin could get you a bled set of front and back basic avids, shimanos etc for around the £100, the So1es are only worth it if you got front and back for £20, I would say...
I've got hayes so1es on my hardrock. to me they are the best brakes Ive every used but then again they are the only hydraulic brakes Ive used. but I dont alter them at all and mine seem fine.