I've been climbing in Scarpa Alphas for two seasons, and I love them. They are plastic, but they are made on a leather boot last, have a low cuff, and are very flexible compared to most other plastic boots. They are designed specifically for water ice and mixed climbing, rather than mountaineering. While not quite as warm as a true mountaineering boot, they are much warmer than Nepal Extremes, etc...which just don't keep me warm. I know lots of people who climb in leather boots, and love them...but the Alphas are definitely a better choice for those with colder feet.