Inception in general comes across as kind of cold to me (It was enjoyable on first viewing, but the characters don't do much for me) but my point of contention is Zimmer's "TIME" theme. It sounds like a good Coldplay song, but not something that feels like a richly composed cinematic track.
Honestly, I've heard better stuff from production houses. TIME isn't "bad" but it doesn't really do the capabilities of symphonic scoring justice.
People have complained about Zimmer's work feeling too mechanical and processed, but with "TIME" I could practically hear Zimmer punch the chords into a computer. It's like the musical texture mattered more than the actual notes.
I liked his music for Intersteller, even though it definately homages Philip Glass.