Here is my take on this.
NWN2 is pretty much like Dragon Age with a bit older graphics (still looking good with some visual mods though). You control every character individually, including their gear, their abilities, etc. The story in the original campaign is so-so, but the companions are really well made, and some quests are hilarious (bard contest, anyone?). The MotB expansion, in my opinion, has the best story ever in a video game, with stunning music, original characters and some interesting moral situations. Storm of Zehir... is great for its customization (you get to make an entire party of 4 from scratch and play them!), but in terms of the story I wouldn't take it seriously. The last expansion, MotW, I haven't played.
The mechanics is D&D, which is harder to learn than DAO mechanics, but it really isn't that bad, and, since the campaigns aren't too difficult even on Very Difficult, you can learn without much pressure.
Now, NWN1... In terms of combat and controls, IMO, this game is abysmal. That is, the combat is quite strategic and requires some thinking in some situations. But you can control directly only your main character, and you can give basic commands to your companions (you can have only 1 companion in the first two campaigns and 2 companions in the last). The camera is clunky, and the movement is choppy. The campaigns themselves aren't bad, but I would definitely not put the first two campaigns on the list of my favorite RPG experiences. The last campaign is good, but a little to long to my taste. The game itself is quite old looking, since it was made back in the awkward days of "ugly 3D", when 3D was only starting showing up in most RPG games (yes, there were 3D RPGs before, and they looked even worse). So, if you are only interested in the official campaigns, I would say go for it if you feel like it, and don't go if you don't have much time to spend (3 campaigns together take a whole lot of time).
Where NWN1 shines however - and that's the reason I play it almost exclusively nowadays - is the toolset and user content made with it. There are countless modules (even though the old Vault is down and the vast majority of those mods are gone, hopefully only temporarily, there are still hundreds of mods available on the new community website), each of which essentially is a campaign on its own; many of them are higher quality than the official campaign, in my opinion. You can play them, which potentially gives you thousands hours of gameplay. Or you can create your own campaigns: the toolset is surprisingly intuitive and easy to use, although scripting can be tricky sometimes. You can also play on persistent words, it is somewhat like mini-MMOs.
It might be hard getting into NWN1 since the game, let's be honest, is extremely outdated by modern standards. Have you played KotoR series? If not, I recommend starting with them, since they have a system very like NWN's (less complicated though, which is good if you are just learning), and the overall gameplay is quite similar. If you have, then NWN1 with some graphical mods may look pretty much like KotoR in fantasy setting would. In fact, this is what the game reminded me the most of when I first played it back in 2013: KotoR! Music has a similar style (I believe the same composer made it, although I've never checked), character development is similar, combat is similar...
If you cannot get past the outdated mechanics and graphics of NWN1, no matter how hard you try, then it might be worth it to just play NWN2. The modding community isn't as big, but there are still enough modules to keep you occupied for a year. I don't know how easy the toolset is to use (most people say it is less convenient than that of NWN1, but I've never checked), but if all you want is play modules, then it doesn't really matter.
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A small trick I found useful: if NWN1 looks too old to you, play through Baldur's Gate 1. After that game, NWN1 will look like a modern RPG, and you will easily get into it. 
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