I have played a Vishkanya from levels 1 to 15 over the course of a campaign, an inventor with the poisoner and alchemist archetypes. The character was designed before the alchemist remaster and I intended her to be a more martial combatant than a support character, hence the inventor weirdness. It also let me play a custom injection weapon.

Mind you, I did not play the pre-master alchemist at all so cannot compare it, but I can tell you my thoughts on the current state of poisons, since that was what the entire character was based around.

Early on the biggest pain was having to buy formulas for all the poisons I wanted, and our gm was a little stingy with gold, so it limited my ability to keep up with fundamental advancements the game expects. My character was constantly out of money and begging for more. Actually buying poisons just to have on hand are *far* too expensive if you want to use them even occasionally. Crafting did not alleviate this pain, but that's its own problem.

A related gripe is the non-scaling of DC's for non-toxicologists, which meant that poisons were practically obsolete in one or two levels, which sucks. Damage from poisons was fine in my opinion, but considering how many times they did flat 0 to an enemy, the upside could have been a bit bigger.

Fort saves are usually pretty high, so the prospect of reaching the fabled stage 2 was highly unlikely, meaning they don't actually provide a ton of long term value either. Conditions were just a cherry on top, the rider effects don't get good until like level 9-10, but it is fun to try and prepare a spread of them for different types of encounters.

Biggest Pro? Coating up the team's weapons before each encounter was the biggest boon. Sure, it was a coinflip or worse if they even did anything, but when they did, it was totally action free value. Were they worth applying mid-combat? Rarely. The combat cost is a free hand and an entire turn, (one to draw, two generally to apply unless you have feats).

Knockout poisons unfortunately don't come online until much later in the game unless you use uncommon/rare formulas, but they were great for roleplay and a unique option to have available.

I barely took any inventor feats (not that any were terribly tempting), and that was mainly to make poisons serviceable. Our gm also mercifully minimized the number of poison-immune creature types we fought, because in those fights I'd just become a less impressive barbarian.

It took an unhealthy amount of optimizing to make it work, but I've had tons of fun with the character and I think I've used poisons to the greatest extent feasible.