There is a reason why this guitar (any J-45) has been around and so popular for so long. It has the "X factor" that people respond to. And it does everything reasonably well: strumming, fingerpicking, flatpicking.
Many people compare it directly to, say, a Martin or Taylor and conclude that it lacks tonally when compared to a very bright and / or twangy example of either of those two. When I was younger, I played all three in a shop before back-to-back and almost immediately dismissed the J-45 as the weakest of the three. Then I came back to it....and couldn't put it down!
The J-45's real strength is in its flexibility and--probably it's biggest asset--how great it sounds as an accompanying instrument to a vocalist. It's sits in a nice punchy zone that isn't too bright and isn't too dry. Why do you think they've been so popular with folkies and singer / songwriters for so long?
And J-45s with some age on them sound FANTASTIC. Playability is also very good...very easy playing neck.
If you're a bluegrass player or flatpicker and want something bright and loud that will really cut through the mix if you're competing with a lot of brighter, louder instruments, I would go with a Taylor, Collings, or Martin. The Martin HD-28s are great for this, for example. The Collings CJ is also very nice, but of course, these are all really expensive instruments!
I say go for it that's what makes you happy and inspires you to play more, man. At the end of the day, if it's worth it to you, it's worth it!
M