Credits to AZImmortal,1 of dvdrbase's supermods:
dvd+r offers a few advantages over dvd-r without having any disadvantages (when dealing strictly with the technical aspects of the formats themselves):
1) base recording speed of 2.4x, whereas with dvd-r u may have discs that can only burn at 1x or 2x---->this is not the case anymore,since speed specs are changed--rw
2)
lossless linking
3) support for
DVD+MRW
4) certain dvd+r writers allow changing of the booktype of the dvd+rs that it writes to "DVD-ROM," essentially making the disc identify itself as a pressed dvd; there are some dvd players that have the hardware capability to play recordable dvds but will refuse to play them if they're identified as so
the non-technical drawbacks are that:
1) dvd-r is slightly more compatible with hardware devices than dvd+r, which is rapidly becoming a non-issue as hardware manufacturers support both formats; being able to change booktype from dvd+r to dvd-rom also levels things a bit
2) dvd+r is slightly more expensive than dvd-r (which will probably change as well)