No, but at level 4 Astarion's main usefulness is to pick locks and disarm traps... which Shadowheart is pretty good at when you add guidance (if you can start YOUR character with a decent Dex you can also fill that role). What Astarion WILL be good for will be sneak attack... but sneak attack doesn't start getting really useful till level 5 (getting progressively more useful each odd level), but personality wise if you are gonna pick one I'd go with Wyll as he is more of the classic hero archatype (if not a tad full of himself at times) where as Lae'zel is kind of "High and Mighty" bitch that starts alot of infighting amongst the group as she thinks her way is the only way.
That is the best way I can describe it with out giving spoilers. Hope it helps
