At the moment, (after a weekend of play) I'm treating it as a single player game, and bits of Morrowind are fantastic – I'm really enjoying the world exploration, and the crafting isn't bad (although my nightblade has moved to heavy armour because I can't get enough leather by whacking deer and other defenseless woodland creatures, but can get loads of iron). Enchanting takes a bit of getting used to, but I think I like that too. The character development is pretty interesting, although I keep getting to level 7 or 8 and wondering what a different class/race/style would be like. But then, I had that problem with Skyrim too.
Inventory is limited to 60 types of thing (max stack of 100), so if you collect all the things, you can run out of space pretty quickly. The lockpicking minigame is quite interesting, especially when you know there are other players sitting next to you waiting for you to fail so they can have a go.
The zone chat uses your ACCOUNT name, not your character name, so if you should pick an account name that you're happy to be public.
Note of warning: you can't use your free month subscription unless you activate a subscription with a credit card, a paypal account, or a time card. There are tales of people being billed the first month using a credit card. I used a paypal account instead. I am still getting billed in Euros, but I don't know if that's a consequence of Paypal.
In summary, it's eating my spare time at the moment, and I think I'm enjoying it more than Guildwars 2, but I haven't got round to trying the PVP yet, and I'm not sure it will hold my attention more than a couple of months.