I've been mapping for 8 years and only put out 8 maps, 9 if you count my upcoming one. It's not that I work slowly, I just take long breaks between maps until the urge to build returns.
Bobsp1 looks painfully primitive now. At the time I suppose it was impressive, compared to other offerings, but I feel it's no longer representative of my skills.
Bobsp2 holds up pretty well. The use of textures and geometry is a bit too ecclectic, but compared to Bobsp1 it's far more consistently designed and detailed.
Bobsp3 is one of my best, I think. I wanted to do something very different from my usual stuff, so I forced myself to build a nature level. Originally, it was to end in a huge battle where you destroyed an enormous radio antennae in a magnificent scripted explosion, but I ended up running out of sectors and so I settled for a multi-tier mothership battle.
I think it's probably best that I leave after BobspX: It's about as good of a level as I am capable of making. The lighting is complex and attractive, the spritework is intricate and occurs frequently, and the level geometry is complex to the point that I honestly wonder if it's wasteful. I am especially proud of the interactivity: Every computer is usable, and you can read the aliens' log entries and progress reports. My intention is to make the aliens seem more living, personable, and three dimensional rather than just being generic bad guys. Also I want to use their dialogue to fully reveal the plot of the Bobsp series.