Gloss and semi-gloss reflect light more directly, which can make a colour look deeper and more saturated in good light but also shows every surface imperfection and can produce noticeable glare under strong or direct lighting.
Practical advice
Gloss is a traditional choice for skirting boards, doors and trim where a crisp, durable, easily-wiped finish is wanted, but is rarely used on whole walls because of glare and imperfection visibility at that scale.
Always confirm with a physical sample in the actual finish before committing to a large surface — see methodology.