The GF4 MX440 is actually quite a major improvement over the GF2 MX400. It has twice the fillrate, supports 128bit DDR-SDRAM hence having at least twice the memory bandwidth, has a higher clockrate, and performs significantly better in real applications/games, supports Accuview, hence having a much less performance drop in AA and better image quality, has an improved memory system(improved caching system, lossless compression, HSA algorithm). It also has 2 integrated 350MHz RAMDACs with 2 CTRC controllers, an integrated TV-out and TDMS transmitter for DVI. In fact, it performs about as good as a normal GF2 GTS.
However, at its price, it doesn't have a very good bang for the buck, when you consider that the GF3 Ti200, GF4 Ti4200 and Radeon 8500LE cost just a bit more than it, and perform quite a bit better, and supports DX8.
So, basically, if you have only $100 to spend, the GF4 MX440 and MX460 can't be beat, but if you have a bit more, spend it on the other 3 mentioned cards.