Largo is an excellent synthesizer with a great sound; I'll let the other reviews speak to that.
I do, however, feel compelled to point out to those of you reading the reviews before purchase that there is one frustrating caveat to owning this synth and NOT owning the dongle: you can only change machines once (and it will cost you money). This is the message I got from Waldorf tech support:
[start message] it seems that you ware using the Soft E-Licenser for storing your License. In this case, your License will be stored on a Harddisk, and can be destroyed because of several reasons. The best way to prevent your Licenses from damage is to store them on the E-Licenser Dongle, and in this way you can also use your Largo License on more than on Computer System. With one License you are able to use on more the one Computer System, but only one time.
We can do a Largo License Replacement but this cost 9,5 € and can be done only one time. That means when you like to have a new Licenser, you need to pay 9,5 € for that Licenser via PayPal and i need a copy of the original invoice (not a copied text, screenshot or photo). You can buy the E-Licenser Dongle in the Shop of your local dealer. We do not sell E-Licenser Dongle. And i would download then your new Licenser on the Dongle.
When you like to buy a new Licenser, please let me know, so i will send you our PayPal Account. Your old Licenser will be deactivated then. [end message].
Last note: at least for me, Largo tended to crash a lot during patch-browsing, so do be careful of that. Otherwise, it's one of the best soft-synths available. ...Real shame about the licensing.
That's the case with any Steinberg eLicenser software. Most developers won't even give you a replacement. The hard disk licenser is primarily for demoing so you don't have to buy a $25 USB eLicenser just to demo the software (like you do with iLok, unless that's changed). The USB licenser is dirt cheap and eliminates all of this trouble. It's not exclusive to Waldorf.