The Soldier class is overlooked due to people mistaking it as the 'shooter' fan route
There are pros and cons against every single class, and Soldier is not exempt to that. That said, you have to go with whatever class you feel that best fits your gameplay.
For Mass Effect 1, it was Adept/Vanguard. For Mass Effect 2, Soldier was my initial feeling, mostly because there are no other pure soldier characters to utilize (except Zaeed, and there are better teammates to lean on) and also because the Assault Rifle is exclusive to Soldiers.
I love all the other weapons, but the Assault Rifle is what I use 80% of the time. That, coupled with Incendiary Rounds (and later) Squad Warp Ammo, it makes short work of all enemies you'll face.
Bring along a tech ally if desired (Legion, Kasumi, Tali) and a Biotic specialist (Miranda, Jack, Samara, Jacob, Thane) and you have all your basic needs. You don't need to go Vanguard to take advantage of the biotic abilities. Just make sure squad usage is off and use the abilities for yourself.
There is no right or wrong way to play Mass Effect. It's defined by how you play, and how much fun you have by doing it. Soldier was very fun for me, and an overlooked one outside the shooter fans.
A fun Soldier combination is to get a biotic to use Stasis/Singularity, then a Tech to do Combat Drone, and follow up with your own Concussive Shot or Adrenaline Rush to line up your shot and blast away.
Adrenaline Rush is excellent for getting out of a tight situation, or when you want to use the Sniper Rifle.
If you're about to die, you can get your teammates to help you out by casting some abilities on foes, and shooting on them to help distract you enough to get off an Adrenaline Rush to give you ample time and opportunity to get behind a cover for your shields to regenerate. To me it is a perfect combination that never really felt out of place.