The ingredients seem to look ok, though I'm not sure what limonene or linalool are. Some type of citrus-based preservatives? *shrugs*
Yeah, citrus extracts. Not sure why they are in there, maybe the smell.

I haven't used this, but I have a couple of issues with it on general principle. I don't understand why someone would add cocoa butter and form this into a block. I guess it is supposed to melt somehow, but I saw someone on hennaforhair talking about having to grate it.

I would be suspicious of the dyes in it being weak and/or old.

I also detect what appears to be some weird misinformation on this site.

Henna works by coating each individual hair like a varnish
What a strange thing to list as a selling point. I assure you, my hair does not seem varnished. Unless I overdid the gel.

There is less worry about re-growth as henna fades gradually and there is no obvious root line.
I don't know what to even say about this, except there are pics of like 20 people on Long Hair Community who are growing out henna, and from the length of the regrowth it has to have been in their hair for years.

I assume you just want it to be red? I would recommend instead to get some body art quality henna from one of these suppliers. If you're in Canada I think that Henna Sooq is supposed to be good. They have half a kilo of Yemeni for only a couple bucks more than one of those bars.