First Impressions

You're better off using daggers because they're quicker but having a dagger in your left hand and a sword in the right will already make you hit faster than you would with two swords, maces or axes. So there's nothing wrong with using a sword in your main hand.

You need 60 points in Cunning to be able to open all locks with one rank in lockpicking. If you go for maximum Cunning which is a rather good idea for a backstabbing rogue (as it also increases armour penetration) you can choose skills that will be more useful for your build (especially since the number of skills is limited).

Picking locks is not essential because of the loot which is rather bad (except a few rare exceptions) it is essential because of all the XP you gain throughout the game for unlocking chests and eventually adds up to make quite a difference.

 

If you don't spread your points too much and focus on Cunning that should be ok. It all depends on the order you're going through the game as some chests are really hard to open early on unless you max out lockpick. In most cases you should be able to go back. I can't think of one that should pose such a problem.

Spoiler

The chest in the abandoned shop in Redcliffe is really hard to pick. I ran into two chests I couldn't open in the Circle Tower but after gaining one level and putting points in Cunning I could open them.

If you really find it hard (because you put more points on Dexterity early on for instance) then you can pick a second rank in lockpick. Each rank is worth 10 Cunning points.

Don't forget that items can make a difference and boost your Cunning and other stats.

Spoiler

If you have the Stone Prisoner then it could be a good idea to invest a few points in Strength and get it to 20 to be able to wear the Helm of Honnleath which gives you a nice bonus to all stats. Don't forget the Fade bonuses from the Circle of the Magi quest. If you do it early on getting your character's Strength to 20 won't cost you so many points.

With maxed out Cunning you have less need for Coercion as well (except for intimidate of course). It's really a good stat to invest into. Cunning also boosts the Bard song (I haven't tried a Bard build yet as I went for Assassin Duelist but it looks like it could have some potential).

 

For the record if you want to pass all Persuasion and Intimidation checks you'll have to max out Coercion.

You don't have to though.

 

Indeed, occasionally, if it is a plot critical check, your comrades will jump in for you, often to comical effect. Just think of Sten and the templar at the ferry when you choose the 'can't we figure something out' line of dialogue

Now easily in the realm of second and third impressions, I really like the way your choices inform the possible choices in other parts of the story.

Spoiler

Killed all the mages and sided with the templars? Well, you can't call on them to solve the Connor quest without killing either Connor or his mother. decided to defile the Urn and have Wynne and Leliana in your party? You're in for a tough fight.

And so forth ... nice, nice.

 

Spoiler

My second play through I sided with the Templars before I went to see what was happening at Red Cliff. So I ended killing Connor's mom, which took a beating on my influence with Alister. Of course that didn't matter because Logain became a Grey Warden and I had Alister killed. He was too goody goody for me. Besides, my PC was going to be the new king and what not. Hopefully I didn't spoil too much for those of you who haven't played the human noble origin.

For those of you who have not taken Logain as a companion I do recommend it. He has some very interesting things to say and he has some really good armor in the game.

 

@Munchkin:

Spoiler

He totally deserved it.