This is MY personal OPINION of MY thoughts. Just so you know. For me...yes it was waaay worth it. I have already gotten two copies and may pick up a third (yes I play with others, and yes, I also like back ups and will pay for said backups if I think the game is worth paying for more than once).
The first questions you need to ask is do you like the SFC series in general. Look at SFC unrelated to SFB, in fact toss SFB out. If SFC kept some of the basic concepts, but tossed out the rules of SFB and replaced them with a 10 - 100 % system...do you think you would like it?
I completely love SFC 3. With the Beta Patch, it is completely worth it, and I imagine when the official patch comes out, it will be that more likeable. I personally enjoy ALL the SFC games, in fact, they currently rank as MY #1 game series EVER. I am a bit rabid in my tastes when I find something I like (I really like Nvidia right now for example) so take that into account. I like Star Trek as well, and SFC 3 seems to do a really good job at recreating the space battles like TNG, especially for a Romulan player like me.
The Single Player game is completely cool, however, I think it is made even better, and cooler if you add a mod...aka...Chris Jones's Complete DW/TNG Mod.
I would say, see if there are any other games you would like. Then have that as a back up. Go somewhere that allows returns. Buy SFC 3. Try it out. Try to find the Beta Patch, or wait until the official patch. Buy it on a weekend. Play the heck out of it. Decide if you like it or dislike it.
I liked it, that's no guarantee that you will, but if you get it at someplace that allows you to return the software, or return for another one of equal value, then you can try it before you settle on it, and if you don't like it...if you did as I suggested, you will have a backup game to fall to when you return it.
Or you could go to Yahoo. I understand or have heard that Yahoo games has a 3 day play period where you can kind of rent the entire version or something like that. You will have to pay some, like a rental, but you can play the game there and see what you think.