Everyone hates on Deep Freeze and admittedly, it isn't a very strong talent however, I think it's worth picking up while leveling (obviously it sucks for raiding but then again so does frost in general).
While I was grinding I took the talent and generally used it on Fingers of Frost procs. When FoF procs, you cast a frostbolt then you deep freeze. What it effectively does is freeze the target for 5 more seconds (as well as stun) so your next 3 Ice Lances can benefit from the triple damage bonus and shatter. Of course you may not be able to get all three ice lances off before whatever you're fighting dies.
Another approach is to start out w/a frost nova from you or your ele, then Frostbolt > Deep Freeze and then Ice Lancex3. It's just another tactic to spice up your solo play, and really isn't necessary or ground breaking but it's not a wasted talent point when you compare it with your other options in a deep frost build. It's most useful against ranged attackers and casters (although Ice Barrier is OP for solo) but it's something to consider. Frost is a leveling/pvp spec in the end, and this talent is useful and fun for both.