I personally like the warlock class a lot and love Hex and ELdritch Blast. If Wyll misses, it's mostly probably because he hasn't darkvision and thus disadvantage in not so well lit areas. Give him Devils Sight and until then, let a caster use a Light or Dancing Lights spell.
What I would change - given Wylls whole backstory - is (as mentioned) to give him higher Dex and make him a Hexblade. Maybe the last one will be changed, when the other subclasses are impemented.
I normally have Shadowheart and Gale in the party, which are for me the two most useful and most likeable characters. Astarion I don't recruit anymore, because I really am annoyed by this character, so in the last spot, I'm alternating between Wyll and Lae'zel. I find Wyll more interesting for the fights, where you are able to position yourself on hard to reach high ground and then pepper your opponents with spells and ranged attacks (liek most of the goblin camp) and Lae'zel in situations, where melee is mostly not avoidable, like the gnoll fights or the minotaurs (basically most of the Underdark).
