It's my sweetie's machine, primarily. I mostly use it when we're out of the house and she decides she'd rather play Plants vs. Zombies on my iPad than do some work :-) So, my remarks aren't coming from the perspective of someone who has used nothing but that machine for an extended period.
We've got the loaded version of the 2010 model, not the current offering. It's a nice little machine, and I've got an old 17" Apple Studio Display (bought with the Ti PowerBook G4 that also brought me in contact with Omni software for the first time) that can be cabled up when the small screen is too confining. I'm not sure I would recommend it for elderly eyes unless there's an up-to-date prescription for corrective lenses. Battery life is okay, portability is great, performance doesn't seem to be an issue as long as you aren't doing anything too CPU intensive (we don't use it to work on our big Aperture library, or convert DVD movies for the iPad). It boots very fast, and the low latency of the SSD makes it pretty snappy even though the CPU is no speed demon. If you want something that's about as portable as an iPad, but better for work requiring a keyboard, it's worth considering. We went with the smaller one for greater portability knowing that we were also going to get a high-end 27" iMac to handle the heavy lifting — if it's going to be your only machine, the 13" might be preferable, with or without an external monitor. Definitely buy it with all the possible RAM, as you can't upgrade that. I understand OWC does sell upgrades for the SSD. I'd say the main regret we've had with it is that we couldn't get this year's model last year, or last year's model a year earlier :-)