Unflavored wasn't that great for me initially, and I just made an effort to see if it would grow on me after a while and it for sure did. I've on occasion tried flavored liquids later on, and always quickly reverted back to unflavored because I'd missed it, and the flavored liquids is just way to much and strange i.e. vaping deserts etc lol.
Unflavored, I don't like the taste of PG, which to me taste like ethanol, so I only use VG, nic and water for thinning. It simply tastes like a neutral slightly sweet pleasant non-intrusive vape, with a little depth and mouthfeel from the nic(just 3mg). If the nic isn't ultra-clean, then it can taste like dirty ashtray. Some clean nics, also add notes like nuttyness and non-ashtray tobacco. If using more than my used 3mg, then the notes are more enhanced of course, and clean nics also gives more than just added mouthfeel and reduced VG-sweetness.
Unflavored is indeed a flavored liquid by itself, and it can be tailored by PG/VG ratio and nic source. Not only that, but certain few VGs can also affect the flavor(unflavored), which I don't know the reason for(water amount, cross-contamination, trace-amounts of source-material or whatever).
Btw, when vaping my unflavored with tighter airflow e.g. MTL, then it's way to sweet imho, and only to me tastes good with more open-airflow and DL.
Unflavored is the only flavor that i've been able to vape for years without getting bored off
Before turning to unflavored, I mostly used simple fruit flavors as they where most long lasting to me without getting sickening, though nothing beats unflavored in this regard imho. I also love the coil-longevity, simple and cheaper DIY and potential health-benefits
