IR was always hit or miss for me. I had experiences much stronger than an equivalent nasal dose, and weaker experiences on much larger doses from the same batch. Probably it was due to fluctuating pH levels, slight differences in technique, or tolerance from other dissociatives.
Recently I got a couple vials and I'm planning to IM some soon. The thought of needles makes me nauseous and I've never used IM or IV with anything, but I've always wanted to IM ketamine in particular, so I'm quite excited. Aside from using nitrous on a few occasions, I haven't used any dissociatives proper in about 7 months, so my tolerance should be down enough to have some great experiences.
I ordered some 25G 1" syringes along with some 0.2 micron wheel filters. The filters are likely unnecessary since it's in pharmaceutical vials, but I'd rather be cautious than not. I want to be alone when I do it, so I'll probably just go with the deltoid.