Fantasy Grounds is not for everyone. If you are one of the pathetic flesh bags that require everything a game is capable of be handed to you on a silver platter, then do not acquire this game, or even Elder Scrolls (let's face it, Steam Workshop is nice, but if you want the good stuff, you have to go elsewhere).
If you get this Virtual Table Top program (henceforth VTT), then be sure to use it with rules sets, as that is where you'll get the most photon blast for your buck. The built in character sheets, the rules sets with drag and drop features, one-click-and-you're-done functionality, it can turn a game session that might drag on in a normal VTT, into a rapid paced session with combats flying by faster than they might in a face to face game. Savage Worlds is an RPG system that banks on being Fast, Furious, and Fun, but in VTT it can drag on if you don't have a working knowlege of macros, or just don't have the time. With Fantasy Grounds, it can be all right there, and a little game prep goes a long way.
There are also a number of free rules sets. Do you play Pathfinder? Well, they weren't able to strike a deal to allow FG to sell paizo products through its store, but they were able to take advantage of the game license to provide the Pathfinder Rules Sets for free. If you dig around the forums, you can even find updates that include books beyond the core rules, such as Ultimate Combat, or Advanced Players Guide. What about AD&D fans out there? Well, OSRIC is free as well. There are a number of sets you can pick up that give you a fan made theme, as well as a character sheet and appropriate NPC/Vehicle sheets, which, while not an entire rules set, goes a long way in making FG work for you. So if you get it, do yourself a favor, look over the website and see what you can scavange.
I currently use this program for Pathfinder, Mutants and Masterminds, and Savage Worlds. I would use no other if I had the choice. However, if you want to get the most out of it, a trip to their website to look at tutorials is almost required.
Connecting to a game can be a pain in the power core. I've opened their magic port and had nothing work, more times than I care to, and there are few things more frustrating than finally having a session start on time, only to be stalled as two of your players cannot connect. If you have a head for networking on these primitive Earth systems, then I imagine it's less of a pain.
Without the use of rulessets, this program becomes little more than an over priced virtual dice roller with incredibly limited mapping capabilities, and some organizational elements. In short, you're better off with Map Tool or Roll20.
Virtal Tabletops are usually designed for their functions, not for their Intuitive UI, some things just don't make sense, thankfully, they have quite a few video tutorials on their website that can get you running a game fairly quickly.
The price counters a lot of the good qualities of this program. I paid for the ultimate license, which cost me the soul of my first born. Considering I didn't want the little brat growing up to challenge my power, it was fine for me, but those of you burdened and weakened by 'morals' might consider otherwise.
Micro Transactions galore! If you hate that, you'll hate this program, as you'll purchase it and then realize you need to fork over more money for your favorite rules set. It's not required, sure, but if you want to use the program the way it is advertised, then it certainly is. I spent over $60 just so I could run Sundered Skies, despite owning all of their books in the first place.
Like house rules? Well screw you! Adding or modifying rules is not for the feint of heart, or those who disdain working with the computational equivalent of simple machines.
The financial weight of this game is on the GM. Period. In my case, this is fine, I run the games, none of my players have to pay a dime to participate, and they get access to all of my rules sets when they join the game. However, unlike a face to face game, a player can't show up, hand the GM a rule book for a system he may not own yet, and have it applied to the game.
Conclusion: I recommend it, if you have the money for it, and if you plan on using it a lot. Otherwise, stick to the free or the cheaper VTT's. Though I will say, when you have the rules set for your favorite system, then there is no better VTT out there.