Do your feet perspire?
Neoprene, and almost all vapor barriers block perspiration from escaping. Your feet generally stay warm while you are moving, but when you stop, your feet (wet by now) get reaaaaally cold. Not very good for multi-day trips or trips where changing of socks is nearly impossible like steep alpine faces etc. Day trips are OK. On multi-day trips, make sure you remove the vapor barrier every evening and change your socks. If you cannot do that easily every day, foot problems will develop in fairly short time. The recommendation to use anti perspirant is a good one, just make sure it is in powder form for cold weather use, sprays and creams freeze.
Some people like VBL systems, some people hate them, rather personal choice. If by climbing, you mean cold weather rock in alpine terrain (?), my experience is that the more you stuff into your boots, the less feeling you have in your feet and again, some love it and some hate it.