When the SE/30 was current, it was well-liked for its small footprint and its power. Even in 1991, near the end of its life cycle, the only strike against it were the 32-bit dirty ROMs (fixable with Mode32). Many were upset when it was discontinued and some even wanted Apple to re-release the SE/30!!
Prices for used SE/30s have been high since the day the model was discontinued in October 1991. Even in 2000, when old Macs could be had for a dollar or two, the SE/30 was usually $10 at minimum simply because of desirability.
For power and RAM expansion, the SE/30 is the way to go for compact Macs. However, the 030 actually will break some software from the earliest days. Since the day it was released, we've been calling the SE/30 "a IIx in a compact case", and that phrase remains true today.
Although I like the power of the SE/30, I actually have a REGULAR SE on my desk alongside my LC. I wanted an SE/30 for a long time, have had three of them, and have kept that regular SE instead. (I sold two and gave one to my cousin). Why? They are still in crazy demand AND the regular, non-030 powered SE is definitely underrated!!
The regular SE is actually the ultimate of original 68000 compacts. It never gets the recognition it deserves because of the SE/30. Think about what the SE itself has to offer: better performance than the Plus, the most reliable analog/power supply of any compact, an expansion slot (it's the only 68000 compact that can get Ethernet without a SCSI adaptor), the ability to have two floppies and a hard drive (or two if you go for that vertical bracket), FDHD compatibility if the board is upgraded, two ADB ports (no other 68000 compact has that), and a cool hard disk access light. (On the ones I use with the kids, I have some fun with those; I have one that's blue and a bunch of reds, yellows, and greens...and even have a pink I may use).
I actually prefer the front bezel of the original SE, and after looking at the SE sitting directly in front of me as I type this, I finally realized why. The SE is more symmetrical with its two larger grooves (for drives). The SE/30 lacks this. This is a personal thing for me (symmetry and color theory are a big part of my home design, which explains why my home SE has a red LED...the LC's monitor has a green one, and they are chromatic opposites or compliments).
On a less personal note, the SE is also a great choice for beginners in this hobby, something which gets overlooked, since it can be purchased with a SuperDrive and doesn't have the capacitor problems of the SE/30. Are there caps on an SE that may go in various spots? Definitely. However, it doesn't rot out on the main board like its 030 counterpart.
Basically, I feel the SE/30 is a good machine, maybe a bit hyped, but still good. However, the SE itself shouldn't have to play second fiddle to it!!