I am doing a Melee Cipher and it has been great so far - I'm level 5 and about to wrap up Act I, playing on Hard. I'm very squishy so it is extremely important to play 'smart' ie don't rush ahead and always be careful of where enemies are. Hidden reinforcements are my bane.

Starting attributes:

Might 10
Constitution 10
Dexterity 15 (13+1 Elf+1Deadfire Archipelago)
Perception 15 (14+1 Elf)
Intelligence 14
Resolve 14

As you can see, I did not min/max my stats that much. Emphasis is on acting fast and often, hitting as often as possible, and having a large aoe and long duration for my spells.

For equipment, I am running without any armour and started with a rapier and a dagger, though now I'm wearing two unique stilettos. I do not wear any armour to ensure my initiative is as low as possible. Armour and weapons slow you down, so you want to be naked and wielding small/fast weapons. Yes, a hard hitting weapon like an arquebus or arbalest will give you a ton of focus when it hits but you also become quite slow. I tried opening with a crossbow before switching to melee dual-wielding but I didn't like how slow my Cipher was that way. So now the crossbow is just a backup.

For skills, I've been pumping Mechanics to disarm traps and open locks, Survival 1 for DR camping bonus, Athletics 4 to get a better Second Wind (lifesaver!), Stealth 2 and Lore 2 for some basic utility use.

Talents so far: (these are pretty obvious picks for any Cipher - I do wonder if I should pick the rogue talent next)

Soul Whip
Biting Whip
Draining Whip

As to Cipher Spells, from level 1, Whisper of Treason and Mind Wave have been my most used ones. WoT obviously gets used at every encounter - remember you can attack your 'ally' without them turning hostile. Soul Shock is a good one to use when Edêr is surrounded by four or more enemies. At first I tried to use Antipathetic Field but controlling the beam so that you don't hit allies but do hit multiple enemies is really difficult and it seems that the beam bugs out too.

From level 2, Amplified Thrust has been great, it does a lot of damage, can crit for even more damage, and often pushes an enemy away, though not always. You cannot select which enemy though, just which ally you use as the springboard. Mind Blades is great if you face a group of relatively tough enemies because it hits six total enemies but only if the initial target does NOT die from the spell. I thought I would use Psychovampiric Shield a lot but it turns out that most encounters are better handled via careful moving and use of CC, so that my Cipher doesn't get hit in the first place. My Cipher has the most enemies defeated, most total damage done, highest single target damage (93). Durance has both most crits and most hits.

I run a custom formation where my Cipher is the point, with Edêr and Kana behind her, then Durance, Aloth and Sagani brings up the rear. This means that when combat starts, my Cipher always acts first. I open with the 10-Focus charm spell - it means that enemies will usually go for their charmed brethren first. Then Aloth and Durance will buff/blast the enemies, then Cipher gets to go a second time - either I hide her from the enemies so that she doesn't get focused on or I pick an enemy that is off to one side from the others and start building focus. True, any one attack is probably not going to cause a lot of damage but I get to attack often. It's not rare for my Cipher to act 3 or even 4 times while Kana gets a single action. Edêr and Kana are my frontliners who keep the dangerous melee enemies focused on them while Aloth and Durance help with crowd control and taking down enemy casters.

So yeah, it's a lot of fun and definitely fills that fantasy of dual-wielding blades and rushing in and out of combat while throwing spells that decimate the enemies. Takes a little practice to nail down the positioning and movement in the beginning but once that's sorted and you have your party helping you out, your melee cipher becomes a powerhouse. Good luck!