Any engine that has a head gasket can suffer a head gasket failure, but the K-series petrol engine was particularly prone to it - in the Rover 200/400, Freelander, MGF, Lotus Elise.
The TD4 is the pick of the bunch.
Freelanders, like all vehicles, have some characteristic problems, none of which are unsurmountable.
To look at Mad Hat Man's list above:
VCU mounts - are two rubber mounts that can wear causing a distictive clunk on transmission take up. They cost <£20 each and have not failed on either of our Freelanders (1998 with 103,000m and 2002 TD4 with 48,000m)
VCU and IRD - The VCU is the bit which gives the Freelander four wheel drive. Early versions were prone to seizing, putting extra strain on the IRD, a clever second gearbox that delivers power to the rear wheels. Early on, many mechnaics that weren't clued up would change a failed IRD, only for it to fail again, because it was a symptom of a problem with the VCU. This gave the Freelanders IRD a bad reputation, until everyone realised that the VCU was to blame. Godda admire the plucky IRD for putting up with it!These parts were redesigned by the time the TD4 came along. There is a simple test for a seized VCU.
Chassis cracks - not heard of this problem as characteristic of the Freelander.
Tyre wear - This was characteristic of early versions, and seems to be caused by either VCU failure or the ratios in the rear differential. Both these parts were redesigned by the time the TD4 came along.
Clongs, bangs - generally down to VCU mounts (see above) or rear diff mounts. Each costs around £20. On ours, one rear diff mount failed at 102,000m, although I can't say for sure that it was the original mount. It gave us plenty of warning with an obvious transmission related "thunk" and it was a good couple of months before we got around to changing it.
Rattles - The TD4 we have is pretty quiet for a diesel. After 48,000m we have a squeak from the mobile phone holder and a irksome knock from one of the doors, which requires a lump of grease every 6-8 months.
Oily engine - Haven't worked on a wide enough range of vehicles to say if this is a problem or not. Would say it is no more dirty than the Fiesta, Rover, Citroen or Mercedes diesels I've experienced.
There's only one characteristic problem with the TD4 that I can think of off the top of my head and that is the Mass Air Flow thingy. Do a search for "MAF". Bear in mind that the TD4 is the acclaimed engine in the BMW 3 Series.
Cheers
Blippie