The split that shows up the second you read the reviews

Here is the number that matters more than the average: in our sample of 100 recent reviews, 54 were five stars and 25 were one star. That is not a product people feel lukewarm about. It is loved or loathed, with very little sitting in the middle.

One thing worth flagging before you read too much into any single comment. Amazon pools reviews for the whole Nutrisse Ultra Creme range on one listing, so the feedback covers everything from ice blonde and vibrant lilac to the natural browns like the Mocha Brown shade. A buyer raving about a cool icy blonde and another furious about a violet that turned red are often talking about completely different shades sold under the same name. When you sort for the browns specifically, the tone calms down a lot, because the wildest disappointments cluster around the bright and lightening shades.

So the trick is to read reviews from people using the shade family you actually want. A one-star meltdown about a vivid purple tells you almost nothing about how Mocha Brown covers your greys.

Red when you wanted brown: the complaint that comes up most

If there is one thread running through the angry reviews, it is colour that lands nowhere near the box. "Meant to light brown. Hair has gone red," wrote one buyer. Another expecting chestnut brown said it "turned my hair red" and described chasing the fix twice with their hair sitting somewhere around orange. The violet and purple shades draw the same fury from a different angle, with several people reporting a pinkish red instead of the cool tone on the front.

There are two plain reasons this happens, and neither is a defect. Permanent dye cannot lighten hair that is already darker than the target shade, so if you have dark brown hair and reach for a lighter or brighter box, the underlying warmth shows through as red or copper. And warm brown shades like Mocha Brown carry red and gold undertones by design, which read stronger on some hair than the photography suggests. A buyer signing as HA gave it four stars for a "warm, rich brown with subtle golden undertones" but still noted the gold was "a bit more prominent than I expected, especially in direct sunlight."

The takeaway is not that the dye is broken. It is that a strand test and a realistic read of your starting colour would have caught most of these surprises before they hit the whole head.

What the repeat buyers keep coming back for

Flip to the five-star side and a different product appears, one people restock without thinking twice. Grey coverage is the headline win. "The colour is perfect for me having grey hair, I find a lot of hair colours go way too dark. But this brand and colour are great and very natural looking," one long-term user wrote. Garnier markets the range as delivering up to 100% grey coverage, and while a few buyers report stubborn strands around the hairline, most in the browns say it does the job.

The cream texture earns its own fans. Because it is a thick creme rather than a runny gel, it does not drip down your face during application, and one reviewer was pleased enough to note it left no stains on the pillows afterwards. The included conditioner, a restoring formula with five oils, gets namechecked even in some negative reviews: one unhappy buyer still admitted "the conditioner was nice though."

Then there is the money. At £8.50 a box, it comes in far below a salon appointment, and that value is the single most repeated reason people stay loyal. "Better than salon results," wrote one 55-year-old who said she had tried nearly every colour going. Another summed up the appeal plainly: it is much cheaper than a hairdresser and does what it says.

About that no-ammonia, vegan promise

Garnier lists this as a gentle, no-ammonia, vegan formula, and plenty of buyers back that up. "It doesn't smell like bleach at all. Is really gentle and doesn't sting like a lot of other brands," one wrote, while another praised the "very little odour" and hair that felt healthy after.

But the smell reports are not unanimous, and it is fair to flag that. A handful of reviewers describe a strong ammonia or bleach smell on opening, and one who normally uses the range said their scalp stung this time when it never had before. Another posted directly that they did not believe the product was ammonia free. We cannot verify the chemistry from a review, and scent perception varies a lot between people and even between batches. If you have a sensitive scalp or react to strong fumes, the sensible move is the patch test the instructions ask for, done 48 hours ahead, rather than taking the gentleness on faith.

Does the colour actually last?

Garnier promises deep, radiant colour for up to 8 weeks, and this is where reviewers pull in opposite directions again. On the happy side you get comments like "long lasting colour" and "amazing long lasting colour," from people who clearly get their eight weeks and more.

On the other side sit real fade complaints. One buyer said most of it washed out after only a few washes and that their daughter's natural colour showed through in three days, even after using two packs. A couple of grey-coverage users reported the grey creeping back within a wash or two despite the permanent label. These reports lean heavily toward hair that was being lightened or that had a lot of grey to hold, both harder jobs for any box dye. If your hair is close to the shade you are applying and in decent condition, longevity complaints are rare. If you are asking the dye to make a big change, temper your expectations.

A related niggle worth knowing: several people with long or thick hair found one box was not enough. As one put it, "I have long hair and I ended up needing two boxes." Buying a second box up front is cheap insurance against patchy, half-covered results.

How to load the odds in your favour

Almost every bad outcome in these reviews was predictable, which is oddly reassuring. If you want to sit in the five-star camp, a few habits make the difference:

• Read the shade name, not the model's hair. Mocha Brown is a warm brown and will show red and gold tones. If you want something cooler, pick a shade labelled ash or neutral rather than fighting the undertone after the fact.
• Match your starting point. Permanent dye deepens and tones, it does not lift dark hair lighter. If you are going more than a shade lighter, this is the wrong tool and you will likely get brass or copper.
• Strand test first, then patch test. A snip of hair tells you the real result colour, and the 48-hour skin test protects a sensitive scalp. Both take minutes and prevent the horror-story reviews.
• Buy two boxes for long or thick hair. Running short mid-application is the fastest route to a patchy finish.
• Check the box date and shake it well. One buyer found the components would not mix properly, a sign of old stock, so a quick date check on arrival is worth it.

Our verdict lands close to the middle, and deliberately so. For someone dyeing greys or refreshing a brown that is already near the shade on the box, this is a well-priced, low-fuss dye with a conditioner buyers praise even in critical reviews and colour that holds for weeks. For anyone hoping to lighten dark hair, chase a vivid fashion tone, or skip the strand test, it is a gamble that too often ends in red. Know which shopper you are before you open it, and £8.50 buys a very good result.