There's nothing wrong at all with FL Studio. It pretty much has everything you need to make good beats, aside from the built-in samples that are $hitty. Just don't use those built-in samples. Sample your own sounds, download or buy samples. You can find a lot of good samples on the internet for free and with a little EQ-ing you can really enhance them to your liking.
However, I do usually export my stuff to .wav format then edit and mix it all in other programs like Adobe Audition, SoundForge or ACID. I think it's best to export the stuff you do in FL like this, that way you can edit the individual waveforms if you have to and do your final mastering. It's a lot harder to do all that just within FL.
So I like to use FL more as a tool, then export the sounds I create in FL for use in other programs like the ones I mentioned above for the final edit and mix down. I usually only do that if I'm really serious about a beat though because I can enhance the quality of the sound better if I export because I can get the most of my DX/VST effect plugins, but if I'm feeling lazy or not too serious about the beat/quality, then I'll just do the mixdown in FL's playlist and do the EQ-ing and what not within FL to the best I can.
FL is the complete package. It's so d@mn easy to use. People only hate on it because of the "Fruity" name and carrot logo.
BTW, if you really want to make some good original sounding $hit, it's a MUST IMO that you use VST/DX plugins. I synthesize most of my basslines, strings, kicks, snares sometimes and other synth type sounds. I love the Novation BassStation/V-Station, Arturia MiniMoogV, Native Instruments Pro-53/FM-7, Synth1, Sonic Charge MicroTonic (uTonic), reFX Vanguard,... VSTi synths especially. There's so many damn VST synths & effects you can get. So FL Studio is very expandable if you look at it this way.