I liked it for what it was - though Battra sort of oozed itself in there whenever Megaguiras was on-screen. The movie itself wasn't half bad - the score was pretty impressive, though I think it fit more in with Kiryu than MG.
Megaguirus was a fun single-use kaiju that had potential, but the ideas just weren't flowing there. Godzilla's attacks were phenominally fun though(
POUNCE!!! 
) and The Meganeuron invasion looked very well done.
Now, based on rumors I heard, could it be that Megaguiras was a bit toned down because this was an adaptation of SONY's draft for
Godzilla 2 or simply lack of imagination?