I've got the istick tc100w. It's ok, temp control isn't too bad. It's compatible with the arctic fox firmware which improves customization options for temp control. The first one died just outside of warranty by a day or two. I got another one and it still works but I only used it for a few months.
There's a design flaw in my opinion, the fire bar pushes on a button internally. That button is part of a small pcb board that mounts to the main circuit board but the only thing holding it on are 4 solder points that make the electrical connections and they're all on one edge. As a little play in the fire bar develops it starts to apply pressure at a slight angle to those solder points. It wiggles back and forth until one of the solder points break and then it no longer works.
For many newer atomizers it's a pretty skinny mod. The firing bar is comfortable to use, I like the shape. It's only 23mm wide though so you're pretty much limited to 22mm and under atomizers. 24mm and wider will have overhang. I like that it can work on a single battery or two (single battery only up to 60w), up to 120w with firmware update and both batteries.
Given the price and what's out now I think there are better options. The istick was fine when it came out but it's been a couple years. Things improve pretty quickly in the tech field. I wouldn't say any mod under $200 (if talking u.s. dollars) is a waste of time, plenty of good mods under $100. The vaporesso switcher and revenger mods are under $50. Just some other options.
https://www.vaporl.com/vaporesso-transformer-220w-tc-box-mod.html
The tesla wye is $35 at breazy.
https://breazy.com/products/wye-200w-box-mod-tesla