While Matt's always been the prime creative force, I think the music really benefited from the input of others. As others have said, Geoff Lloyd was amazing -- there was definitely something missing after Underdogs. I mean, I know Priske plays on the records, but you can't hear a darn thing, and even Lloyd's work in Near Fantastica is drowned out on Avalanche.
I like both the solo records. But on Avalanche I think Matt said, "Now I can do ANYTHING I want!" and decided it'd be a good idea to make a sprawling record with nary a song under 5 minutes, which I think was a mistake and a little self-indulgent. He'd never be able to pull that kind of thing with MGB (Born to Kill excepted). WLRRR is much more concise, thankfully, but the music is a retread of Underdogs. Sorry, it is. Still a good record. There's some very Copyright-ish guitar on it, too -- so maybe Matt's loosening up a bit and letting his band stretch their creative muscles.
I think Matt's a great songwriter and lyricist, but his music has always been a little . . . meh. I'm a fan of the hooks, the words, his voice, but I think he's always needed a sonic boost from other musicians. I will be flamed for saying that and I don't mind. My opinion is that if Matt doesn't let his current or other contributers lend their ideas, the music'll get stale, even if the words don't. WLRRR is evidence of that, but considering how different his last two records have been, I could (happily) be proven wrong with the next one.