At our workshop the best seller is this little workhorse. It features built in fuel tank, full 360 degree steering and a centrifugal clutch (only 1 gear). There are a few things to watch out for however.
This engine is air cooled, but does have an Impeller for exhaust cooling water - therefore don't ever run it out of water as you will damage the pump and run the risk of wrecking the lower unit.
Be very aware that these engines are VERY snatchy - the recoil starter I believe is too short, and does snatch back quite violently if the engine misfires or fails to start - keep a light grip on it and DON't hold the engine with your free hand (trust me from experience, that little plastic handle may look harmless but it feels like a sledgehammer when it hits your thumb!)
Check that the engine idles correctly - when you start it you need to keep the throttle in the start position, thats the strange little symbol that looks like a lightbulb on the grip. You will probably need to keep it in this position for a good 5 minutes before you can actually drop the engine down to the tortoise position. Don't even bother trying to go anywhere before it's warmed up, it just won't behave, I can guarantee you. Also on this point be aware that the prop may well be spinning when you start it - If you need to turn the throttle down to stop it turning then you will have to play with the choke to keep the engine alive - it will stall if you let it drop to the tortoise position when it's first started.
That's about it really - Don't let this put you off, these are great little engines, and they really do go for their size! We have sold loads - and the only problems I've seen so far have been neglect or lack of use!
Ooh servicing - not very expensive, at ours your looking at service charge of £40, plus spark plug plus oil and gear oil and maybe an impeller and VAT on the lot, all in all well below £100 a year well spent.