Any good or not? Well they’re good in their own way.
If you research what’s available and look beyond prejudice then you’re likely to find that Jupiter make very good instruments for their primary market: educational use and ‘community’ music making. Jupiter are based in Taiwan, are long established and sell a large amount of instruments - that should tell you something and they should not be lumped in with Chinese instruments. If you can afford a Yamaha instead then I suspect that you’ll get a bit better instrument at a significantly higher price (that’s been my experience with Jupiter and Yamaha student Trombones) but resale values will be better.
Several years ago I had a good toot on one of Jupiter’s current range of Trombones (age: made circa 2000). I’d definitely be happy enough to buy (great value second hand) or play any of their instruments, however few people would feel them appropriate for higher section Bands. Going back several decades the early Jupiter Trombones were good value and OK (played one as a child), but later instruments are (IMHO) a bit better quality.