For the most part, yes.
I started grad school in August, and I built my second desktop (the i5-2500k config) June 2011. I stopped playing games a little before that, but built the second config to be a desktop to last me for the next 4-5 years (the duration of my program). I spend most of my days studying now, and for my breaks I catch up on TV shows haha. So the desktop was more power than I would ever use (at most I was doing AIM, word, powerpoint, web browsing, iTunes at once). That's why I sold it.
Now I take my MBA to school to take notes on and study off of. Come home, hook it up to my external display and use it as my main. Can't wait to get my ATD though :]
And the 128gb SSD is more than enough for my needs since I have an external drive I use to store my media and photos.
I haven't tried any gaming on this, but I was able to play starcraft 2 and world of warcraft on my '09 13" MBP (base model), and the MBA is better than that so I assume it should be ok? But you can search the forums for people's experiences with gaming on it as it would be more credible than what I could offer.
You can't go wrong either way with the MBP or MBA. What I broke it down to when I was deciding was:
MBP -> better camera (don't care), optical drive (don't care), ability to expand/change the hard drive and memory (thought I would care but don't miss it)
MBA -> lighter, higher resolution, SSD
I think the battery life differences between the two will be negligible depending on usage, and yes you could always put an SSD into the MBP, but overall the MBA was much more convenient for me and I don't regret my decision at all. :]