I have a bunch of 5L mini-kegs. I’ve only used them a couple of times. They’re hard to keep pressurized, at least with the tap assembly I have. I’ve found that once I tap one I need to drink it pretty quick. From a quick search it looks like there might be better tap assemblies out there but they seem kind of pricey for what you’re getting.
I’ve only really used them for beers that didn’t really turn out the way I wanted them to but are still drinkable. Instead of going through the hassle of bottling for a beer I’m not crazy about but don’t want to dump just yet I’ll throw them in the minis. Also, if I make a 5 gallon starter beer that I want to drink I might mini-keg it. I’m planning one of those now actually and the plan is to use the minis.
But generally until I get around to investing in a keg system any beer worth keeping is going into bottles.
I would stick to bottling until you make the move into all-grain, or you’re brewing more than once a month, or in some other determine that you are not going to leave the hobby. Basic kegging (no kegerator, just a keg or 2 and a 5lb co2 tank), is reasonably cheap, and you can always just chill the kegs when you need them, if space is your problem.
I had the TapADraft and liked it pretty well. I always bottled some and put some in the TAD. It worked pretty much as advertised, though I never was able to pull off the force carbing thing.
I didn’t use it all that long, as I got a free CO2 tank and regulator. That let me move up to full kegging. If not for the free stuff, I would have happily continued using the TAD for a while.
Most everyone would tell you to save your money and just get a full kegging setup. That’s fine, but the true cost of kegging is quite a bit more than just the cost of the initial kegging setup. Also, some people just don’t have the space!