I have a good deal of experience with Topaz Sharpen, Denoise, and Mask, and a little with Gigapixel. I downloaded the first 3 earlier this year and ended up buying Sharpen and Denoise. Mask was ok, but not great - it made things a LITTLE easier than in Ps, but not a whole lot, and didn't seem worth the price. Denoise is great - I strongly recommend it. Sharpen is very good as well, but it is only helpful on 50-60% of my pics (although updates throughout this year have improved it significantly, and they seem to be continually refining it). I'd recommend it as well if you can get it on sale.
But I just downloaded Gigapixel yesterday to try it out (you get 30 days to try it) and I'm hugely impressed. So much so that I went ahead and bought the whole suite on a black Friday sale (ended up around $200 with a coupon and they credited me some since I already had Sharpen and Denoise). Frankly, I'm not sure if I'll use Sharpen that much any more as Gigapixel seems to do a better job of sharpening through upscaling. Fewer artifacts and just seems more natural overall (I need to play with my workflow; Sharpen may be good AFTER upscaling). For those skeptical about upscaling (as I was) I'd recommend checking it out - it's not just pixel interpolation. I did one shot of myself from a fair distance where I was fairly out of focus, and it did an amazing job of producing a natural result.
That said, it's not magic, and I think Topaz sometimes oversells the results. I watched a promo video where they took a horribly out of focus shot where nothing was recognizable and used Sharpen to turn it into a completely focused shot. It was so unbelievable that I took a screenshot and tried it myself, and I didn't get anything remotely close to what they claimed. Granted, they were presumably working from a raw image with more info (vs. a lower res screenshot that I had) but still.
Anyway, I'd highly recommend Denoise and Gigapixel, and Sharpen to a lesser degree. Mask is fine if you can get it at a significant discount. They have been great at improving already decent shots I've done with my Mavic Air (1), given its small, relatively low resolution sensor. For the price, they do great work; this is the sort of thing that would require tens of thousands of dollars in computing power until recently.
I do wish they'd integrate their software. I still am not sure how to use Sharpen or Gigapixel together, or why they're separate programs. Sharpen, Gigapixel, and Denoise would be a blockbuster program if they'd put them all together, but as is, it's somewhat annoying having to use them separately (I use them as Lr and Ps plugins, but that still involved launching each separately within the Adobe software).
Finally, I haven't had a chance to try out the video software, though I bought it as part of the package. It looks promising, but also extremely slow. I saw a report somewhere that someone said it took 8 hours to render a 15 second clip using a pretty powerful computer.
