Not having much experience with DAW's, Riffworks is very straightforward and allows you to quickly assemble a tune by layering loops of guitar and building riffs from these loops. One of the best features of the software is the InstantDrummer section which is basically a series of drum grooves which you can place in a riff. Each InstantDrummer contains a series of parts that you can choose from and each part can then be varied by rotating some control knobs. This lets you change the feel of a drum part or add to it's complexity so you can obtain a lot of different sounds from an InstantDrummer collection. There are plenty of InstantDrummers in all different styles you can purchase. If you find auditioning loops and assembling them into a song cumbersome then you will likely really appreciate the InstantDrummer function. If you already have a loop library you can import that but unfortunately the software only supports REX format. I'm pretty sure you can use the IMPORT function but the software works best if you stick to the InstantDrummer files.
They include a collection of built in VST effects which are top notch and are always available to add to a single Riff or an entire tune when you are ready to mix it down.
The Riff feature makes assembling a song quick but might limit users because it's difficult to have parts layer over each other.. i.e. you play a guitar solo and at the end of the riff that contains your solo you would like to sustain that last note over the next riff. This is not possible by recording this as a Riff but you instead have to switch to a "song layer". A song layer is essentially a track that spans the entire timeline, which is determined by how many Riffs you have dragged onto the song timeline. It's pretty easy to understand once you have played around for while but if you start to make changes to the order of Riffs then you have to re-record anything in the song layer as it won't line up with your changes any longer.
Anything you record can be Riffcast to Sonoma's Riffworld servers to share with others. They are behind the times as there is no support to directly to any other social website but you can just export the file and upload it on your own.
Their Rifflink service should be the killer feature as it allows users to collaborate over the internet in almost real time. You can't use this to jam live but as soon as you record a loop it is automatically uploaded to the servers so anyone else in the session will hear it moments after you record it. The only problem with the service is there doesn't seem to be a whole of of activity so you might have to wait a few days until someone opens your session and adds something to it. Seems most users are just content with recording on their own and using the free Riffcast feature instead of collaborating. It's $60/yr which is quite reasonable but becomes harder to justify if you post something and don't see anyone add to it for days.. Something like OHMStudio is much more active and Riffworld needs to shake something up if they want to sell Rifflink bundles.
The software has been on sale for $49 for several months now even thought their website says it was temporary.. for $49 it's a pretty good value and it does come with several full InstantDrummer session and 60 days of Rifflink service.