Four qualities stand out in this shloka. The devotee is always content — not occasionally satisfied when things go well, but fundamentally at ease regardless of circumstances. Self-controlled — master of their own impulses. Of firm resolve — once a direction is chosen, they do not waver. And their mind and intellect are offered to Krishna.
Contentment here is not complacency. It is the settled peace of an elderly grandmother who has lived through plenty and scarcity both, who sleeps soundly whether the house is large or the room is small. Pair that with dridha-nishchaya — iron resolve — and you have a devotee who is both gentle and unshakable. That combination, Krishna says, is what makes someone dear to Him.