On easier difficulties, this power might be useful. The key to using the power well is to have it enabled on a shotgun so that when you charge, you can blast enemies and possibly freeze them. However, it may not be a good idea to buy four ranks for the power as others are more useful. Buy two ranks for this power at most.
Also, due to you being less likely to charge enemies on higher difficulty levels, it doesn't really have any use when playing on anything higher than casual and normal difficulty.
A good power and it's unique to the Vanguard. It's somewhat less useful on higher difficulties though. The fact that Vanguards receive increased shields after using the power for a few seconds does help mitigate the extra damage enemies do on harder difficulties somewhat though. But when playing on normal and casual difficulty, it is quite possible to have a bit of fun with the power, especially when it's used in conjunction with a shotgun armed with Cryo Ammo. It's not as useful when used with other weapons.
As for evolving the power if you decide to, Area Charge might be most useful, though it really depends on personal preference.
This is a great power, especially on higher difficulty levels. When enemies are entrenched behind cover and you can't simply charge at them, it is quite feasible to use this power to draw them out by throwing them into the air so that you can hit them (and possibly make them land on the ground in plain view). The power has another bonus. The enemies' elevation in relation to where you are does not matter. So, they can be above you and the power will still affect them. Also, it's enjoyable using the power on enemies who are close to the edge of a walkway. Knocking them off spells instant death for them.
When choosing to evolve Shockwave, it's a pretty tough choice as to what should be picked. Personally, Improved Shockwave might be the best bet because I've found myself wanting the skill to hit two enemies, but it only hits one.
Pull is probably one power you don't want to invest points into. At least, I never found a use for it due to having access to Shockwave. Plus, you can always bring an ally along who has Pull if you wish to use it.
This is the most essential power for the Vanguard, especially if you want access to a lot of the conversation options. It boosts your paragon and renegade point totals and while it may not offer any powers you can activate, it does increase your health, weapon damage and reduce the recharge time for powers.
When choosing to evolve the power, Champion may prove to be more beneficial because it'll allow you to use your powers more often. Destroyer isn't bad either though, so it really does come down to personal opinion as to which you prefer. I.e., either the damage bonus or being able to use your powers more often.
For your bonus skill, I'd recommend taking Warp Ammo. Not only will it heavily damage enemy health and armor, but it'll also deal good damage to barriers. By choosing this power, it essentially ensures that you can bring down the defenses of any enemy easily on your own without needing to rely on your allies.