here is my take.
i love my nex5
i have minolta 28mm, 35mm, 50mm, 50mm macro, 100mm, 135mm, 200mm and 70-200mm mc/md rokkor lenses i use with the nex5 on top of the two kit lens.
i shoot both video and pictures, and left my canon dslr behind once i started using the nex. it's far from perfect, but it's a great camera.
1. Crappy video mode if that matter to you.
i shoot everything 30p because i just don't get into the novelty of consumer level 24p. shoots great video, and is one of the few autofocus replaceable lens cameras.
2. Lack of lenses.
only as far as sony made lenses go. most people shooting with the nex5 have found the love of old glass, and there are more then enough options.
3. Available lenses being too big which lead to a balance problem.
if you've ever shot extensively with the nex, you wouldn't even notice. i've found even with the biggest, heaviest lenses, it still has wonderful balance and is a great handheld camera.
plus, it won't weigh you down.
i can't tell you how many people with canon and nikon dslrs hanging from their necks have asked me about my nex, and watched jealously as i effortlessly tote it everywhere, even with a couple of lenses in my gear pockets.