Jolly useful, I find mine (Bosch).
I'd be surprised if there's a lot to choose between the main manufacturers, but...
... I've looked at the Makita set like the ones in the For Sale section (a friend has them). They feel a bit heavier than the Bosch stuff and there's nothing like the play in the chuck of the drill/driver that mine has. That said, I don't have a problem with mine for accuracy, although to begin with I didn't like it. I get the feeling the Makita ones are better made.
I find the impact driver very useful on big, repetitive jobs, and great with a socket set for assembly/disassembly work, but it's usually too powerful and with too little control for delicate screwdriving. On studwork, floorboards, etc. it is very fast, and the batteries last longer in it than in the drill (on the same job).
I have a cordless multi-tool, using the same batteries. It is indispensible for DIY work - plumbing, sanding, socket boxes, etc.
Any "multi-" anything must be a compromise. On mine it's battery life (can be short) and dust extraction when sanding (non-existent). If you operate with a hoover in close attendance, the sanding pads last for ages (and it works very well). Without religously stopping and cleaning the pad and surface frequently, the pads clog fast and scratch. I think the other trick with them is to use the slowest motor speed you can get away with. That seems to give acceptable battery life. I really like it being cordless though - much better than something corded.
The battery systems are almost identical from a wide range of "manufacturers". I suspect they come from the same place(s) as very few companies make the cells used and their plants are huge. So the life you get will probably depend on how powerful the individual tool needs to be. I have three packs, and they're just beginning to drop off in performance after about six years. That's quite a bit longer than the expected life of the cells (they age and die even if lightly used). So in that sense I'm pleased, but not looking forward to having to replace them!
Makita have a big advantage in that there are third-party batteries available for them, which will save you quite a lot of money. I haven't yet seen any for Bosch (although I keep looking!). It ought to be possible to swap the outer plastics over between Makita and Bosch batteries, as the connections to them appear to be identical, but I haven't had the nerve to attempt it yet (and I can't work out how to get the Bosch covers off, although they are obviously clipped on!).
Two tips - number your batteries (I use paint blobs). That way you know which one you're using, and which needs charge, etc. The chances are one battery will die before the others (there is quite a lot of variability), and you'll know which. Also, don't let them stay flat for any length of time. Even though there are protective cutouts built into the tools (for when the batteries are almost flat), it still does them no good to discharge them that far and then leave them. Keep the charger handy, and recharge as soon as the battery gets to one bar, ideally before it's cut out.
Hope that's useful.
E.
