Once you get your plane flat, and your iron sharp, it should work pretty well. Fettling a plane takes some getting used to so practice on some scrap wood. I have several planes by Stanley, a #4 and #7, a Stanley Defiance #4 and #5, as well as a Stanley 12Ĺ veneer scraper and a 12-151 spokeshave. I converted the Defiance #4 into a scrub plane. Having said all that, there's pretty much nothing the #5 and #7 can do that the #4 can't also do. The #4 is pretty much a shorter Jack and is so versatile that its what I do 95-99% of everything I do, which is also furniture making.
Mainly I would ask myself, does it do what you need it to do, and are you happy using it? If yes, then great! When I started out a few years ago, my first plane was the Defiance #4. It wasnt as easy to adjust as non-Defiance but it was $20 at an antique shop. The plane iron has to be adjusted with the tap of a hammer but when adjusted, it worked as well as my (newer to me but about 35 years older) other #4. For furniture making, rather than shell out for other planes, I'd suggest getting your hands on a new Stanley spokeshave like mine the 12-151. It'll run around $15-20 on Amazon and then keep an eye out for a router plane.
Just to add, I'd also suggest you check out Paul Sellers on YouTube. He does almost everything with just a #4.
All the best,
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