In my dabblings with electronic music in the past I have used plugin Synths in Reaper, but I notice that with Renoise people seem to use the sampler with “raw” synth waveforms.
I thought it was already pretty intimidating to learn what what the knobs meant on a typical Synth plugin, but when I see these waveforms in the Sampler I am completely lost!
What are the advantages and disadvantages of the sampler approach?
There is just one advantage generally speaking: you can use fx pattern commands with samples.
Advantage? You’ll have wavetable style synthesis with custom waveforms. Also samplers mostly suck way less cpu than analog emulation softsynths. And oldschool tracker people are used to simulating synths with samples a lot - 1st and 2nd generation sample based trackers had no option for “real synthesis” or any plugins at all. Flexibility is choice of waves used, also using not only cycled waveforms but longer loops and long samples in conjunction. What gets lost is custom charakter and juicyness synths use to have, and also modulation options etc.
I think samplers are normally easier to grasp than complex synthesizers? You say you had a hard time grasping synths…if you don’t grasp samplers then, you haven’t really understood those synths. Look at the output of a synths’ oscillator as a waveform (in detail!), and you’ll know what a sampler would use as sample to sound similliar (minus filters etc.). By the way - normally people won’t hand-draw their waveforms (unless for very chiptune like effects, coarse shit) but use stuff recorded from a synth, or whatever.
Well for me it was getting the whole workflow down with the sampler - it’s almost wavetable synthesis, but not quite (entirely) -you can’t put individual fx on each wave-forms (Serum does this fantastically!) on an instrument. (For Renoise 3.0 anyways) And for sure way less taxing cpu usage - unless you’re using sinc.
My Experience
Pros:
Cons:
Not a con nor a pro (depends on the person) but there’s so much more experimentation that’s necessary for sampler-synths. (which is why the effects experimentation is simple in Renoise)
“this means it was edited”
I’m an idiot I didn’t see the FX chain thing on the instrument panel until now https://imgur.com/HZYSvWP
Once you get into the renoise sampler, the per sample modulation sets and the instrument effects chains, you can do anything you tell it to, this includes pads, sounding “analogue”,realisticimitations ofrealinstruments anything you can think of (except feedback loops :P).
Be warned of a rather annoying limitation, the 12 samples per instrument per key limit, as well as the aliasing that occurs from the renoise sampler when not using a high renoise sample rate (setting to 96khz will improve it already by a great deal)
Samples you can modulate, edit, cut, copy, paste, mix, slice, sync, loop or whatever. Lots you can do with both alternatives, but i feel i have a lot more control over the sound when i work with samples, they’re easier to automate and manipulate the way i want.
If you find a VSTi sound you like, Renoise is also able to rip the sound so you get a sample version of it. A very nice feature, when the vsti doesn’t support automation.
All of this even before we talk about the more traditional applications of the sampler: percussion, drums, vocals etc. 
Another point would be that it’s nice to have your ‘presets’ stored reliably in the song and not having to worry about update X causing the old songs to sound strange in one way or the other (although it has happened to me only on a few occasions, it’s still frustrating when it does…). And, also, cross-platform compatibility - I compose on OSX too, every now and then.
As for using the Renoise sampler as a synth, with the new filters introduced in Redux, one of the major weak points of the Renoise instrument has finally been addressed.
so we will get new filters?? for sure?? fantastic!
I don’t think the Renoise sampler-synth paradigm is any better or worse than VST emulations, just different. No easy legato; can’t get the same smoothness with some sounds. I’ve come to like it though. It’s pretty great being able to just layer in another sample to fill out the sound, instead of another whole synth instance; say the sound is lacking a little mid-range grit, just a little, it’s easy to add a distorted saw, transpose it to the appropriate octave, and set it at almost subliminal volume… that’s how I use it, anyway.
Also, it’s pretty easy to set up a keyboard instrument that will sound subtly (or very) different across the octaves, without jumping between synths or using different instances. I like that.