They are awesome for their size. If you buy them from most authorized dealers they are expensive..... to me at least.
The only "problem" with them is they arent 1 ohm stable, which can be a problem for some installs. Providing you get you BTL in dual 2 ohm it shouldnt be a problem.
Some people have problems with them blowing fuses at high output levels. A fix that has worked for some is to swap in 25-amp fuses for the 20-amp ones in the amp. Other than that they seem to be solid... haven't seen any more problems than one would expect from any given amp line.
they are great little amps and sound awsome...id recomend em...and yeah sundownz is right theyll pop fuses on ya...alpines fix...telling its dealers to just swap fuses...I lol'ed when I was told that...