Normal mode is very easy to complete. I did it in about an hour with maybe one or two defeats here and there in total. I blame my useless teammates for those.
I didn't change class at all, so that may have been a factor. I just remember I would get about 80% of my team's kills in each team deathmatch. I haven't yet attempted hard mode because I haven't beaten normal mode in all five classes yet and I'm OCD like that, but when the quest glitch gets fixed, I'll try that difficulty and see how hard it really is.
Just wait until the last level.
Easy if you're level is relatively high for normal mode. I completed it on my first attempt with a level 14/15 engineer.
Just started playing SFH2. I haven't gotten super far since I like to skim through every game. But I'll eventually finish it. I'm playing on normal and it's pretty easy. Once that's all done with I take on the challenges and do it on hard/insane. Teammates are lame but hey can't blame them. Especially on hard mode, don't expect your teammates to get any boost.
The classes in SFH2 seem to be unbalanced - or at least that is what I get out of playing the game.
As a level 23 soldier with level 23 gun/armor and addon, I will struggle in campaign - challenges - custom game even with bots at the same difficulty or at missions where 23 is at the top edge of required difficulty. However, as a Jaggernaught I will streamroll the same exact level while being on level 17 and with a level 8 gun and level 11 armor. The same thing with my sniper. The game favors these two way too much over the others.
After playing it yeah health, armor and one shotting enemies seems to be the key to winning. I completed everything as a level 50 mercenary and just used rocket launchers to one shot everything, but didn't have as much health as a juggernaut which I'm sure would have made some things much easier. Not sure about sniper since his health is low but the range of the rifles is OP, probably doesn't need much health since you can headshot everything before they get near you.