This time around is not a bubble. Bitcoin will have mini-bubbles time to time from rapid upward momentum, but the economy is sound enough to support this new price.
April was a combination of rampant speculation followed by Mt.Gox's trade engine buckling under the weight of the sudden volume, causing an equally large panic and collapse to $50, and leveling off at $100.
Since then-
BTCChina has taken over the top spot in volume, Mt.Gox is no longer the central exchange. Gox again started having issues this rally, but BTCChina held up the price, BTC shrugged and kept going. No flash crash to be seen (aside an expected correction, and from there to new all time highs again)
BTC is nearing a $5 Billion cap. April saw $1 Billion after 4 years. We saw it go from $2 Billion (6 months from April) to nearly $5 Billion in 90 days. The chart has gone parabolic, we might see $10 Billion by the end of the year.
Payment gateways and ease of use is increasing greatly.
Global deployment of local Bitcoin ATMs further diversifying the exchange net
Adoption by very large companies, and lots and lots of small ones tired of being gouged by the failing fiat economy.
All those that said "Bitcoin is dead!" in April have been 110% silenced. Media exposure this time has been much, much more positive than April.
SR shutdown scrubbed Bitcoins filthy image from the public eye (despite it not really mattering as SR replacements, and SR itself, returned ), which BTC barely reacted to price-wise. BTC is becoming a real currency and money to the public.
Overall enthusiasm and momentum is increasing rapidly.
The mining network has been converted from a bunch of fire-hazard looking GPU and FPGA rigs to professional grade mining gear.
It has yet to be seen, but we may be seeing the early days of the exponential rise of Bitcoin. I do see this all to mean a state of critical mass, world adoption is accelerating at a breakneck pace. Nowhere near the end at all to be sure. 2013 was the real Year of Bitcoin, moving from the plaything of tech enthusiasts and hobbyists to serious business and market penetration.
And I for one couldn't be happier to be a part of it