About 2 wks on the MBA 11" i7, and I like it a lot better than the i5. It just feels more responsive, with no more frustrating pauses. The i5 wasn't particularly slow, but it wasn't responsive - it had to 'think' on a regular basis. Slight pauses - nothing awful, but enough that I'd wonder if I had clicked the trackpad or not, then just as I went to click again, it would respond. Just a little annoying. The i7 just doesn't do that. I won't say the i7 is a speed demon, but it's a lot more responsive, and I've never felt that I needed more speed. Battery power has been perfectly fine, as well. I haven't worn the battery down to zero, but I've used it for routine computing (no video viewing, lots of surfing, word processing, large spreadsheet and database manipulation, virtual XP on Parallels) for several hours at a time and still was well over 60%. I think it'd hit 10 hours for sure doing what I'm doing.
So Mavericks is supposed to fine tune power saving further, and maybe that will improve system responsiveness with the i5. Or maybe it's just the i5. Time will tell. In the meantime, I'm really happy with this one and don't feel any need to change things. For now, I would definitely recommend the Haswell i7 over i5 at least for the portable sets that I've tried.